Stop and Swap: Changing A Flat Tyre In Five Steps

Changing a car wheel with a flat tyre is a relatively easy task that can be done safely, provided you follow the rules. Here’s how it can be done in five basic steps, with a few tips to maintain safe progress and make life easier.

1: Stop in a safe place, with a smooth, firm surface

Never, ever try to change a car tyre and wheel on the hard shoulder, it’s better to drive on slowly and risk ruining the tyre. Switch on the car’s hazard lights and have any passengers stand well back and away from passing traffic. Extract the spare wheel and tools from the boot, using the warning triangle if there is one. Switch on the car’s hazard warning lights.

2: Loosen the wheel nuts/bolts

Put the handbrake on, putting the car in ‘park’ if it’s automatic. Remove the relevant wheel trim or the wheel nut/bolt caps, if present. You’ll need the special ‘key’ nut to remove a locking wheel fastening. Next, loosen the wheel nuts/bolts. These usually undo anticlockwise and you should always be pushing down on the wheel wrench, not pulling upwards.

3: Jack the car up

Put a chock under the wheel diagonally opposite to the one with the flat tyre. Place the car jack under the jacking point nearest the loosened wheel – never try to use the jack anywhere else. Wind or pump up the jack until there’s enough clearance under the wheel to allow for the replacement fully inflated tyre to fit. Don’t allow any part of you get between the car and the ground.

4: Change the wheel

Turn the wheel until one of the fastenings is at the top. Remove the other three (or four) nuts/bolts first. Then unscrew the topmost fastening. Lift the wheel off, keeping your back straight and taking care not to slip. Fit the spare wheel, aligning the fastenings. Replace the topmost nut/bolt first, followed by the remaining ones. Tighten the fastenings until the wheel is fully seated on the hub.

5: Tighten the wheel nuts/bolts

Let the jack down completely and set it aside. You can now tighten the wheel fastenings firmly, working in a diagonal pattern.

You can no go on your way but there is one more step, for which you’ll need to go to a car tyre bay. Car wheel fastenings should be tightened properly and a tyre bay will use a special wrench to do this. While at the tyre bay, it makes sense to have the flat tyre repaired or replaced as necessary.

It’s also worth making some preparations before you experience a puncture; these can make life much easier. Changing a wheel is a grimy job so carrying some industrial gloves and a mat or piece of carpet in the car can make life much more pleasant. You may also want to familiarise yourself with the wheel changing equipment. Is it accessible? Is it all there? Is the jack there? Does it need lubricating? Better to find out before the event.

Finally, have you got a space saver spare? These usually have limitations concerning speed and distance. Also, space savers can cause dashboard warning lamps to come on, because they confuse the car’s sensors. Your handbook will warn you if this is going to happen.

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Fascinating Facts About Car Tyres

Car tyres. We tend to take them for granted and, though they aren’t fit and forget items, we tend not to invest too much time in looking after them. Provided we regularly check their pressure and physical state, car tyres generally get on with their job, quietly and efficiently. However, the following facts might open your eyes, about car tyres in general and about particular aspects concerning them.

Imagine fifty-five pence. That shiny heptagonal coin and its small circular counterpart are capital. However, the idea that you are throwing this much away with every gallon of fuel you use is a less than capital idea. Yet, running your car tyres at less than the recommended pressure can cost you 10 percent in terms of fuel economy. As under inflated tyres are harder to move along the road; they give the engine more work to do and this means more fuel is burned.

The law is an ass, said Mr. Bumble, in Charles Dickens’ ‘Oliver Twist’. He wasn’t talking about car tyres but the principle nevertheless applies. The law says that your car tyres must have no less than 1.6 millimetres of tread. Legal? Yes. Sensible? That’s arguable. A mere 1.6 millimetres of tread is generally accepted as cutting things fine. Tyre manufacturers mould two millimetre-deep tread wear indicators into tyres, with good reason. It’s arguably better to comply with the spirit of the law here rather than the letter, as the consequences of an uncontrollable skid in wet conditions cost a great deal more than new tyres.

What makes car tyres grip the road? The different types of tyre – all weather, winter, mud and snow, all terrain and performance – share common elements. The hardness or otherwise of the rubber in them and the tread pattern they have make a major difference in terms of grip, tyre life, on-road behaviour and longevity. In general though, it is the hardness (or softness) of the tyres’ compound and the water-clearing abilities of the tread that make the most difference to the level of grip given.

There’s nothing better than a new set of car tyres, is there? Some have found out to their cost that brand new tyres aren’t necessarily as grippy as their predecessors. The good news is that this relatively lessened grip doesn’t last long. If car tyres weren’t coated in an anti-stick compound during manufacture, they’d never leave the mould. This coating has to wear away before full grip is achieved. So run your new tyres in, driving more carefully for the first 500 miles or so. This is particularly important in wet conditions.

More than 40 million car tyres. That’s a lot of rubber but it is the number of tyres that are disposed of every year. Following EU directives means that comparatively few tyres go into landfill these days. Some are treated to new treads, minced tyres become carpet underlay and some wind up as part of new road surfaces. Plans are in progress to recover energy from old car tyres; they could replace coal in some industries.

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Beating Winter: Car Tyre Tactics For Bad Weather

It’s that time of year again. The days are short, the nights are long, precipitation is up and the mercury’s dropping. Your car’s tyres may be nearly new but there are limits to what they can do. So here are a few tips to help preserve life and limb even in the worst conditions.

There are no such things as magic tyres, despite some people’s believing that their car tyres have prestidigitatory properties. In fog, for example, your tyres won’t stop you instantly, just because you haven’t seen the line of cars up ahead in time. Equally, your tyres can’t suddenly give you enhanced grip because you need to swerve around a similar obstacle. Drive only as fast as you can see.

Rain is another condition that requires caution. Standing water in particular can be extremely dangerous. Car tyres can dispose of surprisingly large amounts of surface water. However, when there’s too much to shift, they ride on the water surface instead. This is aquaplaning; in short, it equals no grip. Drive only as fast as your tyres will allow.

Floods are an altogether different matter. Hitting a large body of water standing a third of the way across a road at speed might give you vicious steering pull but you’ll get through if you allow for this. In deep water, your car tyres will cope admirably but your car might not. Many cars nowadays have a low-mounted air intake. If this inhales water, the engine will be wrecked. Don’t enter floodwater unless you’re certain of its depth. Keep to the crown of the road where the water will be shallowest. Keep the engine revving, to prevent water entering the exhaust and drive slowly – you have a car, not a boat. If in any doubt at all, find another route.

Snow and ice and car tyres don’t always mix. Winter tyres are a boon and it’s worth considering acquiring a set, especially if you live somewhere that experiences these conditions regularly. The usual, all-round car tyres can’t get a grip on ice and snow, even if they’re gracing a 4X4. When conditions are really bad, you may need to consider some additional hardware. ‘Snow socks’ are a new idea. These tough, woven tyre covers are easy to fit, quiet and grippy. However, they don’t last long on tarmac. The alternative is snow chains; not so easy to fit but far tougher, if noisy.

Above all, winter driving requires caution. Grip is always compromised to some extent and if you try to drive normally, losing control becomes a very real possibility. Remember also that your vision is likely to be compromised as well. Remove snow or ice from your car’s glass before moving an inch and always think about stopping distances. Modern electronic aids, such as traction control and anti-lock braking systems help but they’re no more magic than car tyres are. Should the worst come to the worst, and vision and grip both come under the general heading of appalling, you don’t have a choice. Stay at home!

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Baywatch: What Makes A Good Car Tyre Bay?

We’ve all driven past them. Tyre bays might offer the best prices, two car tyres for the price of one, special deals on four-tyre sets and all manner of other tempting offers. This is, of course, just advertising and, as Joseph E Levine said, “You can fool all the people all the time if the advertising is right and the budget is big enough.” Now, it’s true that car tyres are often a distress purchase but even so, knowing what makes is good tyre bay is knowledge worth having.

So, what makes a good tyre bay? The answer is a two-word one: products and services. Here, it is not only the range of products and services but their quality that matters. Here’s what to look for in your car tyre-buying expeditions.

It’s obvious that a tyre bay is there to sell you car tyres. What you need to know first is whether the tyre bay is going to sell you new tyres. If you can, take a look at the stock on the shelves – you’re looking for the DOT codes. If this has three digits, walk away – four-digit codes came in after the year 2000. The way to read a four-digit code is easy to understand. The first two figures represent a particular week in the year denoted by the last two figures. So, a tyre marked 5009 was made very near the end of 2009. Car tyres have a six-year shelf life – and you can always check the tyres’ age before they’re fitted.

Speaking of tyre fitting, tyre bays have this down to a fine art. Given that car wheels and tyres live in a grimy environment, some grubbiness is acceptable even in a good tyre bay. However, untidiness should be frowned upon. If the tool cabinets are well organised, they’re liable to be well equipped. Similarly, tidy floors and a lack of overflowing bins and dead tyres underfoot denote an efficient workshop.

Wheel alignment is a service offered by many tyre bays. The days of the old Dunlop optical alignment gauge, effective though it was, are long gone. If you see computerised, four-wheel geometry wheel alignment, maybe with the involvement of measurement using lasers, you can rest assured that you’re in a good tyre bay. Remember that poor wheel alignment is a car-tyre eater.

Much the same goes for wheel balancing, which is an essential part of tyre fitting. On unbalanced tyre/wheel combinations, car tyres work less well and wear out faster. In the (very) old days, a balancing kit that involved sitting a wheel and tyre on top of a milk bottle was touted. Computerised wheel balancing is the norm nowadays – accept nothing less.

Many tyre bays are no longer transfixed, work-wise. Putting the tyre fitting and wheel balancing machinery into a van, along with an air compressor, equals mobile tyre fitting. You may take advantage of this service and some tyre bays offer a ‘call and inspect’ service, particularly for car fleet operators.

While there are other services offered by tyre bays, such as air-conditioning checks, the above suggest that a tyre bay offering these goods and services is up-to-date as well as on the ball. This in turn suggests that one very important element of tyre supply and fitment will be available and reliable. Never forget that the staff in a good tyre bay can advise you about choosing the best car tyres for your needs.

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Protection Racket: Locking Wheel Nuts Keep Car Tyres Safe

There are certain, indisputable facts in life. One is that car tyres – and car wheels – are expensive. Consequently, the, er, light-fingered among us have been known to lift our wheels and tyres, by first lifting our cars on to a convenient pile of bricks. In the relatively recent past, car alarms have become smart enough to detect when a car is being jacked up and they can tell everyone in the vicinity all about it. This is ‘active security’, which is a subject in itself. In this article, we’ll look at an example of ‘passive security’.

Passive security needs no power source: it is a barrier rather than a whistle-blower. All it need do is be there to be effective. Sometimes, passive security devices are evidently present. However, devices that mechanically prevent car wheels – and car tyres – from being stolen, tend not to shout about it. The thieving fraternity knows what locking wheel nuts or bolts are about and it’s rare for a vehicle to lack them nowadays.

How, then, do these devices work? Their operation really couldn’t be simpler. If you attach your car wheels to your car’s hubs with four or five nuts or bolts apiece, and those nuts or bolts have a hexagon head, the danger is obvious. Replace one fastening per wheel with a fastener that needs a key of some sort to permit it to be removed and the solution is present and evident. Your wheels and your car tyres are as safe as they can be made.

The obvious question that arises is about the key itself. This, rather than being a key as such, is usually an adaptor, which allows a wheel nut/bolt spanner to be used to remove the special fastening it fits. So, what to do with the key, or adaptor? Most people keep it in the boot, or perhaps in the car’s glove box. This means your car tyres and wheels are protected by the car’s alarm. This could be worse, of course, and what is relevant is that you never know when a car tyre needs to be changed. The only watchword exists when you have to leave your car unattended for a while, say in an airport car park. Having seen a BMW on bricks and wearing no wheels, I can safely suggest that if the wheel key had been in Spain or France with the car’s owner, the wheels and tyres would probably have been present when the car’s owner returned.

The locking of car wheels and tyres has been refined to the extent that corrosion and wheel balancing problems are a thing of the past. There are some cheap sets of locking wheel nuts/bolts on the market; these can fail even when used properly, so avoid them. Nevertheless, another question arises: what happens if you’ve lost the key to an unarguably tough locking wheel nut or bolt? One person on the Internet resorted to using a power hacksaw to dismantle the offending wheel and tyre. However, radical resection isn’t really necessary. Car tyre fitters have generally encountered this problem before, and keep a range of tools, at least one specifically designed for this task.

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

More Star Cars - Movie Flyers, On Tyres

The star cars that make some movies memorable often start life as completely standard vehicles. They rarely stay that way and they always attract a following. So let us follow in the tyre tracks of some Hollywood luminaries.

Our first diva was in fact six cars, of which four still exist. In many respects it was ahead of its time; by the end of the first movie in which it appeared, it was running on rubbish. This early green machine, Doc Emmet Brown’s time-travelling car was a DeLorean DMC12 and it first burst on to our movie screens in 1985. A trilogy of movies and many years later, Christopher Lloyd (Doc Brown) is 71, and Michael J. Fox (Marty McFly) is 49, has Parkinson's disease and an honorary doctorate from the Karolinska Instituet. Of the four DeLoreans remaining, two are studio tour stars at Universal, one lives on the ceiling of Planet Hollywood in Honolulu - and the last one is being restored. Some of the cars that John Z. Delorean made still set tyres to tarmac, and some among their number have attained a degree of immortality.

'So cool it hurt' is an epithet that applied to the late Steve McQueen, and his handling of the 1968 Ford Mustang GT390 Fastback he used in 'Bullitt' did his reputation no harm at all.

During the seven-minute, tyre-burning chase sequence with the baddies' Dodge Charger R/T440, McQueen did most of the driving and there was no camera trickery. Both the Mustangs used were given tuning tweaks so they could keep up with the more powerful Magnum Chargers, and one of each was given beefed-up suspension and a full roll cage.

All that drifting car tyre smoke was real, as was much of the San Francisco traffic. One thing, however, was a later addition. The full-blast V8 engine sounds came from an example of the GT40, Ford's four-times Le Mans winning racing car.

Now for a quirky one. What has massive tyres, ten carburettors with gold plated intake pipes, and a huge, Ford Cobra motor? Need more clues? How about Jahns high-domed pistons and an Iskendarian camshaft? Still too techy? Ok then.

Customizer George Barris built the idiosyncratic vehicle in question. It was based on a lengthened 1923 Model T ford chassis and had a custom body. Still struggling? Alright, here are some names. The car was featured in a 1960s TV comedy starring Fred Gwynne, Yvonne De Carlo; Al Lewis played Grandpa. Those who are thinking of Clive Dunn at this stage can go to dunce's corner right now. However, the names Herman and Lily might ring some bells. Yes, it's the Munster’s Koach.

This unique car toured the 'States extensively in the 1970s, and pre-tour, George 'Batmobile' Barris gave it a new paint job. The car now rests in peace, in the 'Cars of the Stars' museum, in Keswick, Cumbria.

Finally, a vehicle with just 114 horsepower from its 4.9-litre, six-cylinder engine is hardly likely to set tyres or tarmac alight, especially with its three-speed automatic transmission. However, the very same vehicle had its charm and made us laugh, even if it was slow. The film 'Dumb and Dumber' featured this 1984 Ford Econoline van, complete with floppy, furry ears, a lolling tongue and a full fur coat. Jim Carrey and Jeff Daniels' 'Mutt Cuts' van didn't stay long but the movie wouldn't have been the same without it!

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Car Tyre Clearance: Making Sure Your Wheels Measure Up

There’s nothing in the rule book that says you must keep the wheels your car had on when it arrived. Many people change their wheels, for a variety of reasons. Some want a different style of wheels, some want wider wheels and most want alloy wheels. A change of wheels usually means a change of car tyres. That is no problem in itself but there is a trap into which a lot of people have fallen with a resounding clatter.

The thing is, any car wheel will accept one or more different sizes of car tyre. There is, however, more to car wheels than just rim diameter and width. Ignore the other measurements or get them wrong and disaster looms. In short, you can find there’s a clash between your car tyres and its bodywork. This can happen with steering or suspension movement and often, it happens just the once, immedately before the tyre and bodywork wreck one another.

The first measurment is Pitch Circle Diameter, or PCD for short. This is nothing to do with car tyre to bodywork clearance but if you get this wrong, the wheels won’t fit. The PCD is the diameter of a circle drawn through the centre of your wheel mountings, be they studs or bolts. The wheels obviously need the right number of stud or bolt holes but you also need to ensure that the wheel nuts or bolts have the right thread and profile for your car’s hubs, and that they are correct for use with the wheels you’re using.

Now for the easy ones: rim width and diameter. You could go for the standard measurements here. However, many people want bigger wheels and low profile tyres. Fair enough – just ask the wheel supplier, who you can always blame if something doesn’t fit. It’s also important to make sure that the wheels can accommodate your brakes. Big wheels and low profile tyres were invented, in part at least, to allow for bigger brakes to be crammed in. These days, clearances are close and it’s problematic if your wheels and disc calipers rub each other. This makes only one difference to the car tyres: they won’t work too well if the wheels can’t rotate.

So, we come to the tricky one, the knotty problem of wheel offset. This is most easily understood with a little bit of theory. Imagine a car wheel sawn in half across its diameter. If you were to draw a line through the centre of the wheel rim, and this line was to coincide with the wheel’s hub mounting face, the wheel offset would be zero. If, as is common, the hub face lies outboard of the centre line, the wheel has positive offset. Conversely, if the hub face lies inboard of the centreline, the offset is negative. The degree of offset, apart from altering wheel clearance, has a profound effect on the behaviour of your car tyres.

Visually, positive offset places the car tyre further under the car’s wheelarch. Negative offset makes the tyre carcass sit further outboard. In either case, provided you don’t choose a seriously large figure in relation to what is standard, the car tyres won’t cause difficuties. That said, there is a danger in choosing too radical an offset, as this figure (usually expressed in millimetres) affects steering. You could find that your steering has becomes mysteriously heavy. Worse still, you could find it’s become over-light, to the extent that straight line driving becomes a thing of the past.

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Car Tyres Teasers - Important Facts You May Not Know

‘We’re on your side.’ This sounds like the tag line in an advertisement but here it refers to the codes on a car tyre’s sidewall. Most of us know the obvious ones like those referring to wheel diameter and tyre section. There are, however, many other pieces of vital information to be found, moulded into the sidewall. Let’s consider some of the more important ones.

Did you know that some car tyres have a marked rating that indicates how well they handle heat build up? If you see a mysterious “A” on a tyre, it has the highest rating. A “C” denotes the lowest.

The traction rating shows how well a tyre can stop you on a wet road. This rating goes from “AA” to “CC”. No prizes for guessing which is the best.

Now for some numbers. Tread wear ratings go from 60 to 600 in increments of 20 and the figure shows how long the tyre is expected to last. In theory, a tyre marked “200″ should last twice as long as one marked “100″. This is, however, a relative rating. The actual tyre life will depend on many factors, including your driving style, the road surfaces encountered, correct wheel alignment and the right tyre pressure. Think ‘benchmark.’

The speed rating a tyre carries is extremely important. Using over-specified tyres is a (very expensive) upside here; tyres for high-speed use can be used at lower speeds. On the other hand, if the speed rating is too low and you have an accident, your insurance company may take a dim view of the tyres your car was wearing at the time. Speed ratings run from “L” (75 mph) to “Z” (150 + mph). Currently, H-rated tyres (130 mph) hold the largest percentage of new tyre sales.

So much for speed, what about load? Yes, car tyres tell you about the load they are capable of carrying, They have a marked load index (LI), which is valid for sub-130 mph speeds. Load indices range from 50 (190 Kg) to 169 (5,800 Kg) but the calculations are a touch complex. Let’s say you have a car that weighs 2 tonnes, or 2,000Kg. Divide this by four to get the weight on each wheel; this equals 500Kg. So far so good, but, do you know that all four wheels carry 500Kg or is one end of the car heavier than the other? In practice, it’s usual to add a percentage to cover such factors.

In our example, then, the car needs tyres with a load index of 84. We can add 20 percent, giving a weight bearing capacity of 600Kg. Therefore tyres with a load index of 90 will do very nicely. In reality, a car tyre’s load rating will exceed its actual needs by a long way. However, when speeds reach 130 mph or more, the load index calculations change dramatically. For reasons far to technical to explain here, the theoretical load rating decreases as road speed rises. In the event you run a very, very fast and heavy car where the speed cameras don’t work, there are experts in such matters. Find one!

Lastly, you should never use a tyre more than 6 years old. The date of manufacture is part of the DOT code marked on one sidewall. For example, a tyre marked “2709″ was made in the 27th week of 2009.

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

A Matter Of Choice - Selecting The Optimum Car Tyres

Car tyres are car tyres, right? Well, they’re all round, black things that go between your wheels and the road. However, choosing the right tyres for your car and, equally important, for your needs is imperative. Here are some pointers to help you make the right choice.

The Right Type of Tyre

There are five distinct tyre types you can choose from and it isn’t always a case of one tyre type for one car; the choice is also about usability.

Standard car tyres, otherwise known as all-season tyres, are the least specialised. They are suitable for year-round use, in wet or dry conditions. In some respects, run flat tyres lie in this arena. Run flat tyres can do exactly what their title suggests; you may continue using them, albeit at a given maximum speed over a specified mileage, even after a puncture.

The third variety of car tyres differs in the conditions to which they’re suited. Winter tyres can handle colder conditions better than standard tyres and they generally have a tread pattern with larger blocks in a more open pattern, for better grip. Our fourth tyre type is also based on the conditions to be encountered, specifically in terms of terrain, rather than climate. All-terrain tyres can cope with mud, sand and gravel and are often found on 4×4 vehicles used off the road. However, the additional grip in adverse conditions has a cost. All-terrain tyres are noisy when used on ordinary tarmac roads.

Lastly in this quintet, performance tyres are for performance cars. As well as offering superior grip in wet or dry conditions, performance car tyres usually have a higher speed rating.

The Right Tyre Size

When it comes to car tyres, it is anything but a matter of one size fits all. The manufacturer’s recommended fitment may be found in your car’s handbook and if in doubt, you could always have replacement tyres like the existing ones. However, small changes in tyre section and width can be accommodated, often beneficially. The staff of a good car tyre retailer will be happy to recommend the best tyres for you.

The Right Tyres for your Driving Needs

While remaining within the manufacturer’s specified parameters, you can ring the changes by using car tyres that suit your driving style and/or particular needs. You may need economy tyres for better mileage from your gallon. Certain tyre types are particularly quiet in use and therefore better for motorway use. Similarly, some tyres are well suited to stop/start motoring. As mentioned above, you’d be well advised to consult the tyre retailer.

The Right Price

The price of car tyres varies considerably but here, commonsense must play an important role. You can’t for example, have economy tyres fitted to a high-performance sports car and expect good results, not to mention longevity. Conversely, there’s little point in having high specification tyres fitted to a car that covers a small yearly mileage. However, if you use your car daily, economy tyres could represent false economy; budget tyres may not last as long as better quality items.

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Top Tips For Pampering Your Tyres

Car tyres are tough, which is fortunate, as they have to be tough to survive. That said, there are ways that your tyres can be given an easier life. Using them can save you money in the long run.

Pressure salesmanship

Running car tyres at the wrong pressure is a surefire way of shortening their life. Underinflated tyres flex more, which causes them to run hot, which makes them pensionable long before their time. Underinflation wears out tyre shoulders, and the lack of air pressure makes them less able to defend your wheels from assaults by speed bumps and potholes.

As car tyre pressure reduces, rolling resistance increases. Meaning? Soft tyres take more fuel to push along. Simples, as that meerkat says.

In its way, overinflation is just as bad. Tyres running on tiptoe sacrifice grip and ride comfort. Overblown tyres also wear out the centre of their treads. Paradoxically, over inflation doesn’t enhance the tyres impact resisting abilities.

A weekly tyre pressure check is hardly onerous. Buy a good pressure gauge and find a forecourt that isn’t so cheeky as to charge for air. You’ll find information about the correct tyre pressures in your car’s handbook and probably on a sticker on one of the car’s door pillars.

A question of balance

When checking your car tyre pressures, you may notice little metal blocks attached to your wheel rims. These are balance weights; they’re there for a reason. Anyone who’s driven a car with a lost balance weight will tell you what the results feel like. A seriously unbalanced wheel will put the integrity of the fillings in your teeth at risk. Equally, anything more than minimal braking will make you wonder why the ABS has deployed, making the brake pedal vibrate like the firing pedal of an ack ack gun.

In practice, even a mildly unbalanced combination of car tyre and wheel will be costly. The increased level of vibration puts stress on several components. The tyres itself will wear faster. The need for the suspension joints to cope with additional strain will cause them to wear. Perhaps more noticeably, you’ll feel the strain too; tyre imbalance increases driver fatigue.

Toeing the line

Wear and tear can put a car’s wheels out of alignment. Misalignment makes cars suffer, and not only in an obvious way. Car tyres like to run straight and if they can’t, they object by wearing out faster. Too much toe-in (cross-eyed wheels) makes the tyres’ outer shoulders wear, and toe-out (diverging wheels) makes the inner edges wear. Apart from being costly, this affects steering sharpness and braking.

Having your wheels aligned and balanced when necessary is a lifesaver for your tyres. Moreover, it is far cheaper than new tyres and possibly a suspension and steering overhaul.

Lastly, drive sympathetically, or you’ll burn out your tyres in no time. Make a point of inspecting your tyres regularly and remember that ten yards running flat will kill a tyre. Your tyres look after you; if you look after them, they’ll continue returning the favour.

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Strategies For Saving - Cut Car Tyre (And Other) Costs

In these dark times, we must all tighten our belts, as well as having them tightened for us by the powers-that-be in Whitehall. It therefore makes sense to do what we can to save on our motoring costs, from saving fuel to making our car tyres last as long as possible. Here are a few hints to deter the wolf from ringing your doorbell too frequently.

Turning fuel into forward motion is a conversion of energy, from potential to kinetic. Maintaining as much of the former while benefitting from the latter involves applying efficient practices. Maximizing mpg starts with starting the car. Cold car tyres are softer than hot ones and cold engines are distinctly fuel-inefficient. So, if it’s a short trip, don’t use the car. Equally, you can save by being gentle on the gas when the car is cold.

Once the engine (and the tyres) are hot, keep to the highest possible gear. This doesn’t mean accelerating hard until you can use top gear. Instead, keep the rev counter needle low on the scale and change up sooner to keep it there. At the top end of the speed scale, observe the speed limit. We all know that speed camera or police radar gun fines aren’t cheap and they increase insurance premiums. It’s also the case that pressing on costs; the difference between 60 and 70 mph cruising can be up to 5 mpg in some cars.

There are several ways in which life can be a drag or rather, drag can be a costly luxury. Underinflated car tyres give greater rolling resistance and increase fuel consumption. Got a roof rack? If you have and it’s empty, dismount it. The air drag of even an empty roof rack is quite startling and you can do without it, and the weight of the rack itself. Similarly, air conditioning is lovely, especially on a muggy day, but it costs. Specifically, it can cost you to the tune of an 11 percent reduction in mpg. This is about balance. Open car windows create aerodynamic drag too. In general, open the windows to cool down around town but at over 40 mph, use the air con.

Underinflated car tyres aren’t the only things that weigh down fuel consumption figures. Some people carry the essentials but if your car is full of junk, every kilogram is costing you fuel. Figure out how likely you are to need golf clubs, dog blankets, Thermos flasks and half a dozen old newspapers on the way to the supermarket. This is a question that answers itself!

Some savings are more obvious than others. The number of miles of tarmac that pass under your car tyres is probably a given. That said, are you using the most fuel-efficient route? Try to avoid traffic if you can and keep up to date with en route road works. Motorways and dual carriageways, without all that thirsty stopping and starting, save fuel, as does the shortest route. Remember that a motorway detour, though a little longer, could be less costly overall.

Lastly, hidden costs. This is all about shopping around. Many things, such as new car tyres, may be what’s called a distress purchase. However, the firms selling the tyres, car insurance, spare parts and even fuel are in distress too. It’s worth looking out for the best deal.

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Car Tyre Calculations: CRF

Looking at the above title, you could be forgiven for wondering, ‘What on Earth is a CRF?’ .As it happens, a CRF is one of those Michael Caine things: not a lot of people know what one is. To put you out of your misery, a CRF is a car tyre science value. It stands for the Coefficient of Rolling Friction. Still mystified? Don’t be - all will become clear!

A CRF is a figure that relates to how much force it takes for a car tyre to be driven along the road. The CRF is used to calculate the amount of drag, otherwise known as rolling resistance, that the tyre has in use. If you need a still simpler example of what rolling resistance is all about, imagine that you’re trying to ride a bicycle with flat tyres. Is it easy? No it isn’t, because the tyres have a high CRF.

We can use our new knowledge practically, to calculate how much force a typical car uses to push its tyres along a road. The force is needed to overcome friction and we can calculate it simply: if we know the tyre’s CRF and the weight it is carrying, we can calculate the force used.

In this example, our car weighs 4,000 pounds and the tyres have a CRF of 0.015. If we now multiply one figure by the other, we can find out the force in pounds. So, 4,000 x 0.015 equals 60 pounds. Does this car tyre science figure mean anything yet? Not really, because we’ve one more sum to do.

The next calculation uses an equation that can tell us how much power the car uses to push its tyres along. The equation is simple enough and we can use it with some figures that are, again, typical. So, Power equals Force multiplied by Speed. Adding figures into this equation shows that the power used is dependent on the speed at which the car is travelling.

Our theoretical car tyres, therefore, use up more power as the car’s speed increases. At 55 miles per hour, they use 8.8 horsepower. At 75 miles per hour, they consume 12 horsepower. Moreover, like with our flat-tyred bicycle, the lower the air pressure in the tyres, the higher the CRF.

Apart from using more power and therefore burning more fuel, what does this friction do? As you can neither create nor destroy energy, it changes its form. In fact, it turns into heat energy. Should the road surface be soft, more heat is transmitted to the ground and less builds up in the tyres.

This car tyre theory is interesting but asking the question, ‘what is it for’ brings an equally interesting answer. Tyre manufacturers sometimes publish CRF figures for their various kinds of tyre. The lower the CRF the less the rolling resistance or, to put it simply, drag. The less the drag, the better the economy. This also shows what is costly about running your car tyres at too low a pressure. However, remember that wasted fuel isn’t the only cost of under inflation.

Lastly, here are the CRF figures for some typical wheel and tyre (and just wheel) configurations.

A low rolling resistance car tyre’s CRF is 0.006 to 0.01

A conventional car tyre’s CRF is 0.015

A lorry tyre’s CRF is 0.006 to 0.01

A train wheel has a CRF of 0.001

Meaningless figures? Look at the one for the all-iron train wheel and imagine how much engine power is used to keep it rolling. As the Americans say, go figure!

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Inflation Rate: Car Tyre Inflators Under Scrutiny

Appearances can sometimes be deceptive. Like the first part of this title, for example. In this instance, the article isn’t about money, or the consumer price index. It can, however, be about saving you money. Buying a car tyre inflator can be a costly business. On the other hand, since a good one makes inflating your car tyres easier and quicker, it will tend to make you carry out this simple chore more regularly. This in turn means your tyres will remain at the correct pressure; you’ll save money by not burning extra fuel to push under inflated tyres along, your tyres will last longer and will be less likely to fail or suffer damage from overheating.

What are car tyre inflators about? They’re a simple electric pump for blowing up your tyres. Yet, a quick look through the available inflators reveals a lot. Some inflators are powered by your car’s battery, usually via the cigar lighter socket. Some inflators are rechargeable. Some are claimed to be quiet. Some are billed as being rapid inflators - one example inflating a tyre from totally flat to full pressure in four minutes. Others aren’t so rapid - one on test took 15 minutes to do its work.

The car tyre inflator’s abilities don’t stop there. Many have a number of LED lights, so you can utilise their inflating facility at night, which could be useful in an emergency. Most are digital, in that they have a digital readout for the pressure of the tyre to which they’re connected. This readout can usually be set to give a figure in the desired scale, that is pounds per square inch, Bar or kPa (Kilopascals).

Another benefit of a good car tyre inflator is that it can do some of the work for you. True, you have to connect it to the electricity supply (or make sure it’s fully charged). You also have to connect it to the tyre you want to inflate and you ought to oversee what it’s up to. However, the majority of good car tyre inflators feature an auto shut off facility. When the tyre is at the right pressure, the inflator stops inflating - it’s that simple.

All this begs a rather obvious question. Which one do you buy? Well, this is not a buyer’s guide. However, we all know that the Internet is laden with user reviews as well as advertisements. You can spend a happy hour doing your research, on which car tyre inflator has the best reviews.

There are some aspects of car tyre inflators that you may want to consider before buying. A quick look through some of the web tests of these devices reveals much. One point relates to a very old, well-worn adage: you get what you pay for. This is scarcely surprising and you won’t get a lot for very little money. You will have the choice between quiet inflators, fast ones, rugged ones and so forth. However, one overarching drawback seems to apply to even some of the more expensive car tyre inflators. More than one test website offers the advice to add a top-quality tyre pressure gauge to your shopping list. Quite a number of the tests discovered that the on-board digital pressure gauges were not necessarily accurate. Comparison will out, of course, during your research. On the other hand, you shouldn’t really need to buy an additional pressure gauge. As a responsible motorist, mindful of your own safety, that of others and the way in which incorrect pressure shorten tyre life, you already have a quality pressure gauge. Don’t you.

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Still More Tyre Trivia: Fascinating, Educational Car Tyre Facts

Low Cunning

Fashion has followed performance, which is why ultra low-profile tyres have become more common. Every car tyre has an aspect ratio, which is a comparison of its height in relation to its width. A ‘full profile’ tyre has a section height that is 80 to 85 percent of its width; such tyres are rarely seen these days, unless a classic vehicle is riding on them.

Aspect ratios have been falling over the years. 70 percent profiles came along, followed by 65 percent, 60 percent and so on. Nowadays, 45 percent profile tyres can be seen on high-performance cars and the current low figure is a mere 35 percent. Beware though, ultra-low profile tyres may look thrilling and they certainly offer tremendous performance. There is, however, a twofold cost. The lower you go, the more ride comfort suffers. What’s more, wheel damage from touching a kerb, or hitting a pothole or debris in the road, is far more likely.

Formula One Facts

A Formula One car can accelerate from rest to 99.42 miles per hour and decelerate back to zero in four seconds. Even though such a car weighs only a little over half a tonne, the breathtaking forces involved clearly give the tyres a hard life. Here are some captivating facts from F1’s sole tyre supplier, Bridgestone.

The company produces 40,000 of its Potenza F1 tyres each year and takes 1,800 tyres to each grand prix.

During the 2008 grand prix season, 19,435 laps were completed on Potenza F1 tyres.

A Bridgestone tyre fitting team can fit 56 car tyres per hour, that’s 14 sets of tyres. Sixty of the company’s personnel attend each grand prix, taking with them 12 tonnes of specialised equipment.

At just over 186 miles per hour, Bridgestone wet weather tyres displace 61 litres of water per second.

Potenza F1 tyres are built to last - for around 93 to 124 miles under racing conditions.

Back to the Real World

Now for some less esoteric facts and figures, from the everyday world of motoring.

About 75 percent of British motorists are driving on under-inflated car tyres.

What this is doing to their carbon footprints isn’t known but it is costing them over 2 billion pounds every year.

Approximately 12 per cent of the cars in the UK have at least one defective tyre.

Another 12 percent have a tyre with less than two millimetres of tread, which is legal but decidedly unsafe.

Ninety percent of Britain’s motorists don’t know the pressure to which their tyres should be inflated.

Continental Tyres carried out a study, which discovered that 40 per cent of British motorists claim never to have checked the pressure in their car tyres.

More than 40 per cent of drivers admitted that they didn’t know how to check tyre tread depth. Seventy per cent had no idea of the legal minimum tread depth, which is 1.6 millimetres over 75 per cent of the tread’s width, in a continuous band.

About 20 percent of drivers confessed to driving on tyres that would probably not meet legal tread limits.

These sobering figures, apart from highlighting the need for a certain amount of education for UK drivers, suggest something else. It’s comforting that the average UK driver isn’t in charge of Formula One car tyres!

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Little Helpers For Car Tyres

In many respects, modern cars are computers riding on tyres. Much of what happens below decks may seem to be under the driver’s control but in fact, computerised assistance is ever-present and sometimes, the computers take over. Here, we can take a look at some computer-controlled elements that specifically relate to the work of car tyres. We’ll find ourselves knee deep in acronyms but don’t worry, each will be explained.

Lets start with ABS. Which is? The Anti-lock Braking System. ABS first appeared in 1929, when Gabriel Voisin, a French aircraft and car engineer, developed a working system for aeroplanes. In the production car world, Chrysler later teamed up with Bendix to produce ‘Sure Brake’. This, a fully computerised all-wheel ABS system was available on the 1971 Imperial. Not to be outdone, General Motors stopped car tyres skidding with ‘Trackmaster’, a rear-wheel only system that first appeared on their 1971 models.

So how does ABS help car tyres? A typical system has a central electronic control unit (ECU), a speed sensor at each wheel, and hydraulic valves within the braking system. Under hard braking, a car wheel that is rotating significantly slower than its counterparts is on the point of locking. The ECU detects this and commands the appropriate hydraulic valve to reduce the braking force at that wheel. As the wheel speeds up again, the ECU reimposes full braking force - this can happen up to 20 times per second.

What does this mean in practice? When the ABS keeps the car tyres at the point of locking but doesn’t let them lock, the car is being braked to the limit of the tyres’ adhesion. This represents maximum braking efficiency. Moreover, skidding car tyres have actually lost their grip. The driver may be applying maximum braking force and locking the wheels but braking and steering control are lost. Under the influence of ABS, it becomes possible to still steer the car around an obstacle.

Now for another acronym, which describes a system that has evolved from ABS. Electronic Stability Control, or ESC, adds two further sensors to the ABS armoury. The first, a gyroscopic sensor, can detect when the car’s direction of travel doesn’t accord with the position of the second, the steering wheel angle sensor. The ESC’s software can then apply braking force to up to three of the wheels individually. Consequently, the car tyres’ grip is used to assist in making the car travel in the direction the driver has chosen. CBC, or Cornering Brake Control, is a refinement in ESC. This system can control the ABS, telling it that the wheels on the inside of the curve being taken should be braked harder than the those on the outside. It also dictates how much additional braking force is applied.

Paradoxically, an ABS-related system can help car tyres to retain grip under acceleration. A Traction Control System, a.k.a. A TCS, detects a driven wheel that’s spinning and briefly applies braking force to allow the spinning car tyre, or tyres, to regain traction. More sophisticated TCS systems can control the throttle level simultaneously, cutting power to the spinning wheels.

As you can see, these electronic aids to safety are complicated. Different manufacturer’s calling them by alternative names further complicates the issue. For example, some call their TCS an ASR, an Anti Slip Regulator. The above is a very simplistic explanation of such systems and there are other, similar systems in use. The bottom line is that they all help a car’s tyres make maximum use of the grip they offer.

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Belt-Tightening For Beginners: How To Cut Motoring Costs

In the wake of the Budget, we can do our own budgeting and save money on motoring. Attending to everything from your car tyres to the way you drive can save your hard-earned cash and help you avoid a deficit of your own.

1: Check Tyres Pressures

Air is no longer free at many forecourts but checking your tyre pressures frequently can save you much more than the few pence it might cost. For a start, running car tyres at too low a pressure increases their rolling resistance. This makes the engine work harder to push the car along so fuel consumption suffers. Underinflated tyres wear out faster too.

Correct tyre pressures improve a car’s handling, road holding and braking. These checks can cut your fuel bill by 10 percent and increase your car tyres’ useful life.

A major upside of checking tyre pressures in that you can look over your car tyres at the same time. Being caught with unroadworthy tyres can attract a fine of 2,50 pounds.

2: Research Insurance Needs

The recession has increased competition in most industries. Car tyres have become cheaper but insurance premiums have become highly competitive. Shop around for the best deal and make sure you’re paying only for the insurance you need.

3: Don’t be a Drag

Correctly inflated car tyres won’t be too helpful if your car is being held back aerodynamically. Trundling around town with the windows open may be enjoyable but open windows equal aerodynamic drag. The same goes for a roof rack, which can impose a surprisingly high amount of drag, even if unloaded. So, remove the rack when it’s empty. Also, tidy out your car. Carrying anything you don’t need costs fuel.

Air-conditioning also saps power; switching it off unless you actually need it saves fuel. That said, aircon is a more efficient cooling medium than open windows at above town speeds. It’s a question of balance.

4: No Short Trips

Cars run inefficiently when cold. Even the most efficient can return single fuel consumption figures for a surprisingly long time when cold. So, try to use your car only when you know it will warm up fully. The same aspects apply when warming your car, particularly on cold mornings. Drive off as soon as you start the engine - a car engine running at tickover from cold uses a lot of fuel, warms more slowly and can suffer more wear. Here, the car tyres make no difference!

5: Plan Your Journey

Longer routes, stop-start driving, unnecessary mileage and diversions all have a negative effect on fuel consumption. Use the Internet, the radio, TV and your satnav to plan your journey. Avoid rush hour traffic jams, steer clear of roadworks or accidents, and try to use motorways wherever possible. Bear in mind that the shortest route may not be the most efficient; more miles under your tyres can work out cheaper in some cases.

6: Observe Speed Limits

Speed limits have always been in place for public safety, even if many have also become a political issue. Remember that travelling at 60 mph costs less than travelling at 80 mph and wears tyres less. Equally, remember that fines and points on your licence also increase insurance premiums. Moreover, you generally can’t argue with a speed camera or police radar gun.

7: Drive Carefully

With a few exceptions modern cars are powerful enough to be lively but burning your car tyres’ rubber on a regular basis, though fun, can be expensive. Fifth gear can give 20 percent better fuel economy than third can, provided you don’t select it too early. Tyre-shrieking starts and lurid cornering are best left to your imagination - and they wear your car tyres out faster.

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Car Tyre Physics: How Car Tyres Behave Under Pressure

Car tyres obviously play a huge part in letting cars take corners. Few people consider how they do this in a scientific way but knowing about the forces at work is both interesting and educational. Why? Because understanding what’s involved and the terminology that applies can help your driving.

In road tests - particularly in track tests - cars are referred to as having understeer or its opposite characteristic, oversteer. These terms are directly related to car tyres, but what do they mean? The short, smart answer is simple: understeer means you’ll see what you’re going to hit, oversteer means you won’t. The less drastic explanation refers to the behaviour of car tyres when great demands are being on them. An understeering car’s driver will feel the need to apply more steering input to make the car go round the corner. An oversteering car’s driver will have to apply less steering input to successfully negotiate the corner. In drastic oversteer, he’d have to add counter steering, or opposite lock. Most cars understeer, for safety’s sake.

What is the science behind understeer and oversteer? Once again, it’s about car tyres; specifically, it’s about their slip angles. What are slip angles? Something that is easily understood when they’re explained to you.

Every car tyre has a contact patch, the area of its tread that’s in contact with the road surface. Imagine the tyres of a car that’s taking a corner. Each tyre will be following a path in the direction the driver is steering. Each contact patch will be following a path but it won’t be the same path the tyre’s carcass is following. This is because the tyre’s carcass deforms in response to the forces acting on it - the lateral force imposed by the weight of the car, and any forces of braking or accelerating. So, the tread in the contact patch follows a tighter curve than that the wheel/tyre combination is following. The tyre tread’s ability to deform locally also has a bearing on the slip angle. The slip angle is the difference between the two paths.

What, then, do slip angles do? In fact, they add grip, up to a point. Slip angles increase with increasing forces, speed included. As they increase, grip improves, until the car tyres begin to lose grip.

When car tyres begin to lose grip, one of three conditions results. When the slip angles of the front and rear tyres are the same, neutral steering occurs. If a car has 50/50 weight distribution and if its front and rear tyres offer identical levels of grip, it will have neutral handling. At the limits of grip, a four-wheel drift will occur; competition cars aim for these characteristics. A car in a four-wheel drift is cornering as fast as it can, nearly at the point of sliding off the track.

Should the car tyres at the front have a larger slip angle than the rear tyres have, understeer will result. As well as being more controllable, understeer can be used to scrub away excess speed on a racetrack. After the ultimate limit of grip, an understeering car will leave the track while going forwards; it can’t corner tightly enough.

What happens if the rear tyres’ slip angles are the greater? Under these circumstances, the grip of the rear tyres will be less than that of the front. The car’s tail will slide towards the outside of the corner. In extremis, the car will spin.

In practice, many aspects affect understeer and oversteer. These include which wheels drive the car forward (front, rear or all, four), the weight of the car and how it’s distributed, whether the car is accelerating, cruising or braking, and the speed and loads involved. However, this explanation gives an insight into your car tyres’ dynamic performance.

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Replacing Runflats With Conventional Tyres

We are receiving a number of queries from tyre dealers concerning customers who want to replace the runflat tyres fitted on their vehicles as original equipment with conventional tyres

Some people, it seems, do not like runflats, for a number of reasons; one of which is the higher price of runflats when they have to be replaced. Another reason is that the availability of runflat tyres could best be described as patchy and, when one has to be replaced, if the tyre dealer cannot supply one straight away then the motorist is stuck.

The situation is exacerbated by the confusion – in the tyre trade and among the general public – about whether or not runflat tyres that have suffered a puncture can be repaired. Take BMW, many of whose vehicles are fitted with runflats as OE, who recommends that punctured runflats are not repaired "as additional forces and wear have been incurred within the tyre whilst being driven deflated". The motorist may feel aggrieved that his runflat tyre not only costs more than conventional rubber, but also that the tyre dealer refuses to repair it, whereas if it were a conventional tyre, then it could be repaired.

However, by far the most common reason for replacing runflats with conventional tyres is not down to economics, but is the perceived quality of the ride – take a look at any online message board and, when it comes to runflats and comfort, hardly anyone has a good word to say about them.

The sidewall is stiffer on runflat tyres and, where these are fitted as OE, it forms part of the suspension, giving a harder ride, according to runflat critics. Of course, much depends on the driving style, but a typical message board comment is along the lines of "I couldn't believe the ride improvement when I got rid of the runflats". One suggestion is that fitting a non-runflat when the suspension had been set up for runflats makes the ride "wallowy" which contrasts with the original hard ride.

Whatever the reason for changing to conventional tyres, it is interesting that some motorists are willing to forgo the undoubted safety advantages of runflats. Also, as more and more cars are fitted with runflats as OE, presumably there will be more motorists wanting to switch.

For those who do decide to switch, what happens should they suffer a puncture? The tyre pressure monitoring systems – which are mandatory with runflats – will work equally well with conventional tyres, so a slow leak can be checked in time, but what if there is a sudden blowout? This is another question frequently asked on the message boards and the answers given are "carry a spare in the boot" (presumably given that there is room) or "carry a can of sealant".

INDUSTRY THOUGHTS

So much for why people want to change over from runflats, but what do the various sectors of the tyre industry, vehicle manufacturers and insurers have to say on the subject?

Back in 2005, the British Tyre Manufacturers' Association issued a statement concerning self-supporting runflat tyres (SSTs). On the subject of retro-fitting conventional tyres to SST-equipped cars, it points out that this "would remove the runflat capability, potentially leaving the driver immobile in a case of deflation and could compromise vehicle handling. It is therefore recommended to consult with the vehicle manufacturer or tyre manufacturer before replacing SSTs with conventional tyres."

Tyre manufacturers' websites have little to say about replacing runflats with conventional tyres. Most recommend replacing runflats with runflats and not mixing different runflat brands. One thing they all agree on is that runflat and conventional tyres should never be mixed on a vehicle.

Regarding the criticism of ride comfort, no doubt tyre manufacturers would argue that, in the early days of runflats, this may have been the case, but would point to the improvements in construction and materials since then, making the latest generation of runflats the most comfortable yet.

It should be remembered that the growing use of runflat tyres is because they are popular with vehicle manufacturers, not because the tyre industry wanted them. The BTMA statement suggested contacting the vehicle manufacturer, so we approached BMW, as an enthusiastic supporter of runflats, for their thoughts on changing to conventional tyres.

Their statement began by listing the reasons that they chose to utilise runflat technology in the first place, which primarily focused on driver and passenger safety and comfort. The statement went on:

"All of our vehicles that use runflat technology have their suspension and braking components set up to accommodate runflat tyres. Should you decide to change to non-runflats, it may alter the driving and handling characteristics of your vehicle. It is for this reason that this modification is not recommended by BMW as a manufacturer.

"However, it is possible to have standard tyres fitted. You will additionally need to purchase either a spare wheel with jack and brace set or a mobility kit, which can be ordered from the parts department of your nearest BMW Approved Dealership.

The illustration above shows a normal tyre deflated and on the left a run-flat tyre deflated clearly showing the additional sidewall support from the run-flat.

"Converting a vehicle from runflat tyres to conventional tyres will not invalidate its warranty, although this could give rise to a warranty claim being rejected where the fitment of conventional tyres is found to be directly attributable to the occurrence of any fault or defect."

So that's it – it can be done, but BMW doesn't recommend it.

TyreSafe statement

What about TyreSafe, the UK tyre safety group – where do they stand on this issue? We contacted them and, a few days later, a statement was released. In it, TyreSafe warns motorists that they could be compromising their own safety if they replace the run-flat tyres fitted to their vehicle with standard tyres that do not include run-flat technology.
The statement goes on: "With many motorists looking to reduce their vehicle maintenance costs, some have been tempted to economise by selecting tyres which do not incorporate the added technology and features found in run-flat tyres. By choosing these standard tyres, drivers risk significantly changing the handling characteristics of the vehicle which could increase their chances of being involved in an accident.

Stuart Jackson, Chairman, TyreSafe says "As a general rule, we would always recommend that drivers only replace run-flat tyres with a similar product. Run-flats have much stiffer sidewalls than those in traditional tyres and this is taken into account by vehicle manufacturers when they design their suspension and steering systems. By switching to tyres that do not use run-flat technology, the handling of the car can be dramatically altered and it may become unsafe, particularly during extreme manoeuvres."

In addition to the performance changes which may occur as a result of switching to non run-flat tyres, drivers can also cause themselves other problems. Run-flat tyres give drivers the ability to continue their journey for a limited time when they have no pressure in the tyre. Standard tyres cannot do this and must be changed as soon as there is a sudden loss of pressure.

SAFETY AND INSURANCE

The most powerful argument against getting rid of runflats is the safety angle. While punctures at high speeds are relatively uncommon, the results can be devastating without runflat capability. However, this is not the only safety factor, as, back in October 2006, Auto Express carried out a tyre test comparing runflats and standard tyres against each other on a wet and dry track.

A sentence in the report said that “fitting the wrong tyres to your vehicle could also invalidate your insurance”. Is this, in fact, the case? We contacted insurance giant Aviva and asked whether swapping from runflat to conventional tyres would affect a motorist’s cover.

The answer was unequivocal, with the Aviva spokesperson saying: “I can confirm that there would be no issue with a motor insurance policy purchased directly with us if a car was changed from runflat tyres to conventional tyres, with the only stipulation being that the tyre was road legal. We would only advise the client to call us so that this was noted, but there would be no additional terms imposed.”

We tried to obtain an industry-wide comment, but without success and the sensible course of action would be to check with your insurer before changing over tyres, to be on the safe side.

WHAT ABOUT RETRO-FITTING RUNFLATS?

In addition to replacing runflats with standard tyres, some NTDA members have been approached with requests to retro-fit runflats to cars that normally carry conventional tyres.

There is little information on this subject, but one thing for sure is that some sort of tyre pressure monitoring system will be needed. As you might imagine, the Royal Society for the Prevention of Accidents (RoSPA) seems to be a fan of runflat technology and it has the following to say about retro-fitting runflats:

"You should seek expert advice from your vehicle manufacturer before retro-fitting a runflat tyre if your vehicle has TPMS. As the tyre is more rigid, vehicles that have them as standard may require softer suspensions to compensate for the lost ride comfort. Guidance should also be sought from the tyre manufacturer."

Star Cars - Silver Screen Objects Of Desire, On Tyres

Who makes a movie? Usually, it’s a joint effort. In some films, however, it isn’t only the actors, director, crew and backroom staff that make the result memorable. It’s a car or cars and here are some we all know and love…

Roald Dahl and Ken Hughes scripted the 1968 film ‘Chitty Chitty Bang Bang’. Dick Van Dyck and Sally Anne Howes appeared in it but its specially-built star made it come alive. There were in fact six Chittys and not all ran on car tyres. One was the car in its dilapidated state, another appeared in all its rebuilt glory. Of the four others, the ‘hovercraft car’ is probably best remembered. This variation was lightened with aluminium copies of many of the brass parts. When the car had to be filmed suspended from a crane or helicopter during ‘flying’ sequences, its engine was removed to lighten it further.

Could you create a legend in just over seven weeks? In August 1965, US custom car builder George Barris was given a job to do. He had to produce a special car for TV and film work, as fast as possible. Luckily for him, a division of the Ford Motor Company had built a concept car ten years earlier. The Lincoln Futura made an ideal starting point. Barris fitted the 390 cubic inch (6.4 litre) V8-powered car with 15 inch cast alloy wheels, carrying Firestone Wide Oval tyres. Into the recipe went Cumming & Sander impact safety belts, a Moon aluminium gas tank, 2 Deist parachute packs with 10ft. diameter parachutes, and the ‘exhaust turbine’ was made from a five gallon paint can. If you need any further clues, the giveaway lies in the colour scheme. Threequarter inch fluorescent cerise stripes relieved the ‘Velvet Bat-Fuzz Black’ surface finish. Yes, we’ve been looking at the original 1966 Batmobile.

Now for a collection of vehicles, all but one of which set tyres to tarmac in reality. In 1969’s film ‘The Italian Job’, it wasn’t a real Lamborghini Muira that went into a river. It was a bodyshell on a crash-damaged chassis. However, when the film crew returned to pick up the pieces next day, they’d been stolen overnight!

Speaking of car tyres, the production crew got through quite a number with the Italian Job Minis. These were Mk.1 Austin Mini Cooper S cars; in the hands of stunt driving team L’Equipe Remy Julienne, they became legendary.

The film’s two E-Type Jaguars were Series One models, bought for a measly (for the time) £900 apiece. The red convertible registered 848 CRY, however, was restored and survives to this day. Michael Caine’s character’s 1961 Aston Martin DB4 convertible, scooped off its tyres by a digger, really did go down the mountainside - twice. In fact, the first take was unsatisfactory because the car was supposed to burst into flames (it didn’t because the man with the ‘explode button’ had to run for his life as the Aston plummeted towards him.) The ‘Aston Martin’ that we did see destroyed was a Lancia Flaminia 3c Cabriolet, dressed up by an excellent and obliging bodywork firm in Turin.

To close this little trip down memory lane, we can look at what is arguably the world’s most famous coach - ever. The six-wheeler that ended up with its rear tyres clawing at empty air at the close of The Italian Job was a Harrington Legionnaire. Perhaps the notion of reinforcing the cab so that the boarding Mini Coopers didn’t squash the driver was heralded with this: ‘Listen lads, I’ve got a great idea - er - er’.

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Rising Damp - How To Cope With Downpours And Floods

Here in the UK, 52% of our days are overcast. Rain is a given and it is frequently very heavy. Consequently, we should be used to it and there is no excuse for ignoring it. It is also a fact that even car tyres in prime condition inflated to the recommended pressures can struggle to cope, especially in particularly heavy rain and floods.

In heavy rain, you need two things, grip and visibility. Good wiper blades and a full screenwash bottle are essential. Doubling the distance to the vehicle in front is equally necessary. When the rainfall approaches biblical proportions, you could encounter standing water. Car tyres are designed to offer a grip by clearing water from the area that contacts the road surface. In extreme conditions, they can no longer sweep water away quickly enough. This can lead to a phenomenon called aquaplaning, in which the tyres skim along the surface of the water. Should this happen, you may find out the hard way.

How? Try to brake and very little will happen because the tyres have no grip; the same goes for steering control. A sudden, suspiciously light feel to the steering is an excellent clue to aquaplaning and the ‘cure’ is to gently lift off the accelerator; you will feel the tyres regaining their grip. Nobody who’s experienced it would deny that aquaplaning is frightening. Should it happen, it will quickly educate you into matching your road speed to the prevailing conditions.

Sometimes, rainfall becomes so heavy that the roads’ and their drainage systems can’t cope with it. Here, flooding is not only a risk, it is practically a certainty. The secret of coping with significant flooding is to employ forethought. ‘Look before you leap’ is a long established proverb and in many respects, it applies to flood driving. You shouldn’t attempt to drive into floodwater without knowing how deep it is. Tall 4×4s apart, modern cars have an engine air intake positioned quite low down. The snag is that water, unlike air, is incompressible. Should water enter the engine, the pistons will be stopped dead in their tracks. This will completely wreck the engine.

So, what do you do when you see floods ahead? A simple rule of thumb is that being able to see the road surface means you can see how deep the floodwater is. Assuming you can see the depth of the water, flood driving goes like this.

Drive straddling the white line. Being on the crown of the road puts you where the water is shallowest.

Drive in a low gear, at a slow pace. Creating an impressive bow wave is a very good way to drown your engine but keeping the engine revving will prevent water’s entering the exhaust and causing a stall.

Should the engine come to a dead halt, it’s likely the worst has happened. Depress the clutch immediately and do not attempt to restart the engine. Damage may already have occurred; turning the engine will make it worse.

Should another vehicle be approaching from the opposite direction, make every effort to let it negotiate the floodwater first. This is for two reasons. One, if you both have to move across to let one another pass, you’ll both be in deeper water. Two, if the oncoming vehicle ingests water and dies mid-flood, you’ll be prompted to not try negotiating the flood yourself.

Finally, remember that brake pads can ‘aquaplane’ on wet discs, leaving you without brakes. On leaving the flooded area, apply the brake pedal for a short while, to dry the discs.

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Pre-Loved Pointers: Used Car Buying Tips

‘Caveat emptor’ is Latin. It means ‘Let the buyer beware’ and it makes the perfect maxim for anyone intending to buy a secondhand car. The rules for a successful purchase are simple enough and making a matchless deal is easy if you use these pointers.

1: Check the tyres. Car tyres save your life on a daily basis, simply by doing their job. Tyres with 3 millimetres or less of tread need replacing. Tyres can also be excellent tell tales. If they’re worn unevenly, the car’s suspension, steering or brakes could be at fault. Cracked tyres are generally pensionable and lumps or bulges in tyre carcasses suggest internal damage. Remember to check the spare tyre and bear in mind that tyre failure can be a killer.

2: Check the VIN. The car’s Vehicle Identification Number should match that in the logbook. If it doesn’t or is absent, the car could have been stolen, ‘rung’ or be two half cars welded together.

3: Check the history. This advice counts in two ways. Dealers must offer an HPI check by law. If buying privately, have one carried out yourself. An HPI check is to validate the car’s history and would reveal previous damage, theft, insurance claims, writings off and more.

Service history is equally important. If a main dealer or an approved concern has carried out servicing, the car’s automatically a better prospect.

4: Check the deal. Often, dealers can offer a warranty. The car may have some remaining manufacturer’s warranty and there may be ’sweeteners’, such as included accessories. Be very careful if buying from a private seller. Once the car is yours, you have very little comeback if it proves to be a bad buy.

5: Check the car. Unless professionally executed, accident repairs are easy to spot. Look for poor panel gaps, paint colour and texture mismatches, non-factory additions (e.g. lights) and damaged exterior trim. Take particular note of the car’s extremities: the nose and all four corners. Suspiciously thick, new-looking underseal can hide a lot, as can the boot carpet.

Look under the bonnet, for a clean engine bay with no rust or coolant stains. Dip the oil, which shouldn’t be like black treacle, and look underneath the car for spots of leaked fluid.

6: Check the mileage. The car’s MOT certificates should show a believable progression of mileage figures and the speedometer’s mileage reading should tally. Modern electronic mileometers can be easily tampered with so checking that the speedo screws aren’t butchered doesn’t always reveal a clocked car. That said, plastics and modern trim can wear. If the steering wheel rim and the pedal rubbers are shinier than the bodywork, chances are the car has an intergalactic mileage in reality. A worn, bursting drivers seat, is a dead giveaway, as are badly worn driver’s door mechanisms. Don’t forget that these parts could have been replaced, so if they look too new, be wary.

7: Check the performance. Have a realistically long test drive, using the vehicle as you expect to on a daily basis. Try the brakes, steering, transmission and electrical items. Should something be not as expected, be careful to not fall for the old ‘They all do that’ routine!

8: Remember these three golden rules. Unless the car you’re examining is so rare that there simply isn’t another, you can always find a rival example. Rule two: it’s a buyer’s market at the moment and you can always walk away. Rule three is simpler still: buy with your head, never your heart!

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.

Snow Joke: Driving in the Deep Midwinter

Car tyres do a magnificent job. Few would argue with this but there are those who seem to believe that their car’s tyres can perform miracles. Most people who’ve seen the consequences of this belief would argue with it. Now that winter is upon us with a vengeance, knowing what car tyres can and can’t do, particularly on snow and ice, becomes particularly helpful. Here are some basic facts to begin with…

* Car tyres, like many shoe soles, are made of materials that provide grip in most conditions. On snow, car tyres provide much-reduced grip and on ice, can offer practically no grip.

* Treating the road surface, with a mixture of salt and grit, enhances the available grip.

* This enhanced grip is nowhere near that provided by even a wet road surface.

* Should the treated surface re-freeze, the level of grip will decrease radically.

* Loss of grip equals loss of control.

Ok. For those who would argue that their car has anti-lock brakes and traction control, there are further facts. Electronic aids notwithstanding, a car (or a van, truck or whatever) can only obey the laws of physics. ABS, DSC and other driving aids help but like car tyres, they can’t perform miracles.

So, how do we deal with snow and ice? The short answer is very carefully but there are ways of driving in such conditions. Let’s take a look at the most useful…

* When setting off, you can lose traction. A car with furiously spinning wheels won’t be going anywhere except possibly downwards. Be subtle with the controls and in really bad conditions, try setting off in second gear.

* Should your car tyres insist on spinning, you may be able to progress by using wheel spin but only as a last resort. Turn the steering repeatedly from lock to lock and you might, just might, find a little traction.

* In adverse conditions, driving becomes very much a matter of the balance between grip and sliding. This is an immensely delicate balance that’s easily upset. Your fingertips and the seat of your pants give the best feedback about what’s happening at ground level.

* Despite all the theoretical talk, your car can only skid in three ways. In understeer, the front of the car loses grip and runs wide. In oversteer, the rear loses grip and tries to pass you. In a four-wheel slide or skid, all the wheels lose grip. If you’re skidding, you’re going too fast for the conditions.

* If the front wheels skid (understeer), reduce the amount of steering you have applied. In a rear wheel skid (oversteer), steer in the direction the tail of the car has taken. In all cases, four-wheel skid included, lift off the accelerator but avoid hard braking.

*If your ABS cuts in under braking, you may have a limited amount of steering control. Again don’t expect miracles.

* Where traction and grip are radically limited, stopping distances increase vastly. Never, on any account, follow a vehicle too closely and be aware that what’s behind you could have only a minimal chance of stopping. Should a vehicle be following too close, pull in and let it pass.

* Remember that even a treated surface can refreeze. Pay attention to your car’s ice warning and act on it. Black ice can remain in shadowed areas long after sunrise.

Above all, be realistic. Should conditions be dreadful, accept the fact and don’t travel. With the abovementioned driving aids, not to mention seatbelts and airbags, you’re likely to survive an accident. However, surviving the consequent insurance issues and the inconvenience of repairs can be a major hassle.

If in any doubt at all, you need answer one question, the one that posters carried during World War Two: Is your journey really necessary?

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.