Thursday 13 December 2012

Car Tyre Caution. Negotiating Floods

Floods have featured heavily in the news media lately. We've just experienced the wettest summer in UK history, and the consequent flooding has affected a number of cars. In some instances the results have included fatalities. Your car tyres may provide as much grip as you need – until your car starts to float. Yet the tyres won't stop a car sinking, or being swept away. Here's how to deal with floodwater.

There you are, driving along, minding your own business. It's pouring with rain but you're perfectly confident about your car tyres' abilities on wet tarmac. Then it happens, you're faced with glossy sheen of floodwater in your path. Your thoughts begin to race. 'Should I keep going, or turn round?'; 'Will I get stuck?'; 'How deep is it?'

Depth is the very first thing to consider in such a situation. In most instances, a car can handle floodwater as deep as its wheel rims – the car tyres will be submerged but they'll cope. The snag is; how do you gauge the depth of the water?

There is no simple answer to this question. You may have local knowledge to tell you what to expect in a given location. You may have a good view of the white line, or you may have just seen another car successfully wading through the water. There are, however, warnings to consider. For example, you can bet your car tyres that a flood stretching away out of sight, such as around a blind bend, is liable to get deeper. Similarly, your seeing a big 4x4 happily paddling doesn't mean your saloon car will manage.

Apart from your car tyres' role, the major element to consider is your engine. All engines compress the fuel and air mixture that enters their cylinders. A petrol engine may squash the mixture by a factor of fourteen, while a Diesel engine might compress the mixture to twenty-five times atmospheric pressure. Here's the rub: you can compress air, you can compress vapourised fuel but you cannot – repeat cannot – compress water. A surprisingly small drink of floodwater will instantly stop whichever pistons encounter it. However, the connecting rods will still be pushed upwards by the crankshaft…but not for long. Broken or bent conrod(s) – for which read 'scrap the engine' are the inevitable result. This is exacerbated by many modern cars having a low-mounted air intake. Cool air drawn form low down equals improved combustion. Water drawn into the air intake equals a dead stop.

What, then, is in our line of defence before we try to dip our car tyres into floodwater? Local news, via the TV, radio or Internet, are helpful sources, provided you pay attention to them. It's also a great idea to have a fully charged, functional mobile phone with you, just in case. Remember that, if you encounter a flood, asking around – especially if the police are present – could save your life, let alone your car.

Now for the worst-case scenario. You arrive at flood and have to decide on how to tackle it. Stop and take a look, getting out of your car unless you're 100% sure of the water's depth. Is the white line, or the underwater tarmac surface visible? If so, remember you can go to about the depth of your car tyres' sidewalls in most cars. Is the water still? If it's rushing, forget it – unless you fancy being on the news. Moreover, if someone starts beeping at you to hurry, invite him/her to go first. You'll know what to do if this car suffers a grinding halt.

Assuming you plan to go for it, put your trust in your car tyres and go slowly forward. Use a low gear, so that the increased engine revolutions will allow the exhaust gases to keep the water at bay. Go slowly, so as to not create a big bow wave – which might just drown your engine. And remember to stick to the crown of the road, where the water will be shallowest.

Finally, though your car tyres will dry off after a few revolutions, your brakes will stay wet. Lightly touch the brake pedal until you feel the brakes bite again.

Article Resource

Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Life Lessons. How To Maximise Car Tyre Life

Maximizing your car tyres' useful life is as much about being both safe and legal as it is about saving money in the long run. Your car tyres may not receive too much of your attention but a combination of forethought and maintenance will help you achieve the very best results for your car tyres.

Buy the right tyres

Car tyre choice is a matter of making an educated selection. So-called 'long-life' tyres may perform as advertised but can have downsides. They are liable to be noisier in use than 'normal' tyres, whilst also being less grippy. Similarly, 'normal' tyres could save you a few pounds but could let a higher performance car down grip-wise. The solution? Trust your tyre fitter.

Make sure your wheels are properly aligned

Given that wheels running out of alignment spell an early demise for car tyres, it's worth having a wheel alignment check at tyre replacement time. Significant misalignment will show in odd wear patterns on the tyre treads, and can make the steering feel odd.

If you've encountered a big pothole, road debris, or have had an argument with a kerb, get the alignment checked as a matter of course.

Use the right pressure



You can usually find this out from a sticker on your car's doorpost, or from your user manual. Too little tyre pressure can cause fuel-wasting drag, excessive tyre flexing and tyre failure through overheating. Too much air in your tyres can lead to premature wear and unreliable handling.

Drive with sympathy

…,for your car tyres, that is. Consistently taking corners at 9/10th of your car's (or your) abilities shortens tyre life. The same goes for aggressive accelerating and braking. Movie stunt men don't have to pay for their car tyres!

Give your tyres a break

Following on from the previous tip, this kind of mechanical sympathy specifically concerns physical damage to your car tyres. We have, for our pains, got to put up with speed bumps and speed pads on our highways. We don't, however, have to let them damage our car's wheels and tyres.

The way to tackle these devices is to treat them as what they are – hazardous to your car tyres. Always cross them slowly. If you come across the kind of speed restrictor where there's one speed pad per carriageway, never straddle them. Instead, let the wheels on one side of your car traverse them. Also, try to avoid touching a kerb, far less mounting one.

Driving like this will protect your car tyres, as well as greatly reducing the chances of expensive and/or dangerous damage to wheels.

These are proven practices that will prolong the life of your car tyres. They can also help save wear and tear on your car's wheels, suspension and steering. Don't be misled by knowing that car tyres are very tough indeed. They are tough but they aren't invincible. Pay attention to the above and stay safe, and you will save money by not having to replace your tyres before their useful life ends.

Article Resource

Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Monday 19 November 2012

Eight Car Tyre Challenges: What Affects Tyre Life

All car tyres wear – they are, after all, consumable items. However, some car tyres wear faster than others. Let’s take a look at eight aspects that affect car tyre life.

1. Wheel Alignment

When your car’s wheel alignment is correct, the tyres can run true on the road. This means that a balance exists between the car tyre’s drag and the amount of compliance in the car’s suspension. Incorrect alignment spells increased wear, and can affect your rear wheels as well as the front ones.

2. Speed

Continuous high-speed driving accelerates car tyre wear. If you doubt this, just take a look at Formula One – pit stops aren’t to give the driver a rest while the tyres are changed!

3. Driving Style

If you drive sympathetically, your car tyres will last longer. Drive aggressively and you’ll pay for it through having to replace your car tyres sooner. An aggressive driving style will raise car tyre flexing and running temperature, and increase tread wear.

4. Car Tyre Placement

On a rear-wheel drive car, the front tyres must cope with steering and braking while the rear tyres offer traction as well as grip. On a front-wheel-drive car, the front tyres have still more to do, consequently wearing faster.

5. Vehicle Weight

Heavier vehicles wear our car tyres faster than lighter ones. There are, of course, heavier duty car tyres to compensate for this to some extent. However, the basic principle remains.

6. Car Tyre Type

Car tyres are constructed to meet particular needs. A performance tyre will give superior grip but will wear out sooner, as it has a softer rubber compound. Conversely, a harder, long life tyre will offer a longer life, at the cost of lesser grip and increased noise. There are tyre types that offer a compromise between the various demands on car tyres.

7. Tyre Pressure

An underinflated car tyre flexes more, runs hotter and wears faster than a correctly inflated one. Underinflation also increases fuel consumption, by creating additional tyre drag. Overinflation is nearly as bad, causing strange wear patterns and reducing grip.

8. The Passage of Time

This is the one aspect affecting tyre life that can’t be avoided. Ultra violet light causes rubber to degrade, as do chemical spills on the road. The usual giveaway is the appearance of cracked sidewalls…themselves indicative of a car tyre that is old. A car that is garaged will receive better car tyre life than a car that lives outside.

As is now clear, the factors affecting car tyre life – and performance – are many and varied. Mechanical sympathy and assiduous car maintenance positively affect tyre life. Conversely, it isn’t really surprising that bad habits can affect tyre life negatively.

Article Resource

Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Changing a Car Tyre the Professional Way

Back in the mists of time, motorists used to change their own tyres – by hand. No doubt there are diehard enthusiasts who still do this but for us mere mortals, there are car tyre bays. Here’s how a car tyre is changed – by machine.

To be attended to on a tyre machine, the car wheel with the tyre to be replaced must be taken off. Enter the trolley jack and powered wheel nut wrench. Almost without exception a key or adaptor to cope with the locking wheel nut is needed now. Soon enough, the errant car tyre will be detached from the car, complete with wheel.

Now the fun begins! We’re contemplating separating a big, tough rubber ring from the big, heavy metal wheel it’s been embracing, probably for many miles. The tyre fitter can unscrew the tyre valve and let the air out, but he can’t make any impression on the car tyre/wheel combination without mechanical assistance. This is why the tyre machine has powerful, compressed air-powered jaws, better known as the bead breaker. With the deflated car tyre placed correctly, all the fitter need do is press on a pedal. The jaws seize the tyre and separate the bead from the wheel rim.

The failed car tyre now has to go up in the world. More accurately, it has to lie flat on the tyre machine, with the wheel clamped firmly in place. More compressed air is used to let the machine seize the wheel firmly. Then, the fitter will place the hooked head of the tyre machine by the car tyre’s bead. Lifting the broken bead carefully over the wheel rim with a tyre lever, the fitter will flip it over the machine’s head. Another press of a pedal releases compressed air, causing the wheel to rotate. The tyre machine’s head peels the upper bead of the car tyre up and off the wheel rim. Repeat the process for the lower bead and that’s it – the old car tyre is off.

Now for a spot of wheel preparation. The old tyre valve’s inner fitting is sawn off and the valve is drawn out. The old balance weights will be peeled off or unclipped and, in some instances, the fitter will use a hand wire brush to clean corrosion off the wheel rim. Then, after having replaced the tyre valve, the fitter will apply a special compound to the wheel rim and the new car tyre. This stuff is a lubricant that will make fitting the new tyre easier. However, where there has been an air leak between the old tyre and the wheel, the fitter will brush on a special sealant.

The tyre machine comes into play again now. Once cleaned, lubed (or sealed) and re-valved, the wheel is ready to accept the new car tyre. The machine is simply used in reverse order, the push the new tyre over the wheel rim, bead by bead. Using a compressed air line, the fitter will then inflate the new car tyre. Sometimes, the tyre/wheel will need encouragement to seal but the tyre will eventually seat itself – sometimes with a loud bang – when air pressure builds up. Throughout the car tyre-fitting process, the tyre machine has done most of the heavy work, while the tyre fitter carried out the intelligent tasks.

So, are we finished? Not quite – the wheel and car tyre combination need to be balanced. There’s another machine for this. Having placed the wheel on the tyre-balancing machine and clamped it on firmly, the fitter will close a safety guard and start the machine. The machine spins the wheel up to a given speed, which is usually about 200 revolutions per minute. Now it’s the balancing machine’s turn to be clever. Using its sensors and electronics, the machine will tell the fitter how heavy the balance weights need to be and exactly where they must go. Using the machine’s recommendations, wheel weights will be fitted and the newly balanced wheel taken up to speed again. Fine-tuning can be done but it’s rarely needed.

What used to be done manually, and could lead to sore hands and backache has been done quickly and efficiently. Should you watch from the comfort of the waiting area, you’ll know exactly what the fitter was doing at each stage of the tyre change…and why!

Article Resource

Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Monday 12 November 2012

Merityre News!!

Building will shortly commence at MERITYRE SPECIALISTS LTD, West Way, Walworth Business Park, Andover, to extend the existing retail tyre depot. Two new bays should be operational early in the New Year, adding an extra 50% to the current space available for fitting tyres, batteries exhausts and brakes.

The existing Merityre building was constructed in 1988, as a purpose built warehouse and Head Office for Merityre, which currently has a further 21 Tyre and Exhaust Branches in the South of England. The retail fitting bays were part of the original design, but were limited in size due to Test Valley Borough Council planning restrictions at that time.

Now that Andover is seeing the expansion of its housing stock at both Augusta Park and Picket Twenty, the increase in business at Merityre has prompted this expansion, to improve customer facilities and reduce waiting times during busy periods. Merityre is open for business 7 days a week, from 8.30am – 6.00pm Monday to Friday, 8.30 – 5.00pm Saturdays and 9.30am – 12 noon on Sunday mornings. Local branch manager Paul Kinnaird, and his assistant Craig Denness, are looking forward to these new facilities and remain committed to providing a top class service on Tyres, Exhausts, Brakes and associated products in 2013!


Friday 12 October 2012

Car Tyre Care. A Significant Investment

When you drive out for the first time on a brand new set of car tyres, you’ll probably be experiencing one of two feelings. You may have a sense of pride in the knowledge that you’ve had your tyres replaced after getting the full life from the previous set. On the other hand, you may feel frustration. Why? Because you misused or neglected your old tyres, making the new set into what retailers call a ‘distress purchase’. You had to replace your car tyres early, when a little car tyre care would have put off the evil day.

It would be naïve to expect a set of car tyres to last indefinitely – they are consumables after all. However, bad driving habits, poor road conditions and mechanical faults can limit the lifespan of car tyres. Let’s look at some of the more common causes of premature tyre breakdown.

Much as your continuing health can depend on your car tyres, the health – and lifespan – of your car tyres largely depends on you. Yes, you can drive on the limit, squeaking your rubber on the Queen’s highway at every opportunity. Alternatively, you can drive more, well, let’s say soberly, and increase your car tyres’ longevity.

Though you can’t choose the road surfaces on which you drive, you can drive according to the road surface. We’re not quite at Third World status in this country but the combination of heavy traffic, severe winters and saving money on repairing the damage these do; means we encounter some bad roads. Car tyres are of necessity tough but they aren’t indestructible. When you find yourself driving on a particularly poor road surface, slow down. This gives your tyres an easier life and gives you time to steer round potholes.

There are also road ‘surfaces’ that can be detrimental to tyre life. Traffic-calming measures (some call them ‘traffic-harming measures’) such as speed bumps and speed pads can damage your car’s tyres, steering and suspension.

These devices are designed to make you slow down. The sad truth is that if they don’t do this sooner, they probably will later, to your cost. Rule one is to never straddle a speed bump. Your car tyres and suspension are not really designed to take a load that effectively pushes them outwards forcibly. Straddling speed bumps can lead to increased tyre and suspension wear, and misalignment. Instead, drive so that the wheels on one side of your car pass over the speed bump. Hint: if driving alone, let the passenger side wheels take the strain.

You can’t avoid full width speed bumps and speed pads, even for your car tyres’ sake. You could, of course, press on regardless but even big, butch 4x4s can suffer damage from excessive speed over speed bumps.

The other car tyre killer isn’t so much a road surface as a piece of street furniture. Kerbs have their rightful place in the scheme of things. Your car tyres have no right to be traversing or hitting kerbs. Yes, your car tyres have a cushioning effect, so you can lightly touch a kerb if it confirms your position during parking. However, with low-profile tyres and alloy wheels being so common, raked rims are all too evident. Look at a few parked cars and you’ll see the results of car wheel to kerb contact. Just bear this in mind: if the wheel rim is gouged, chipped or cracked, what’s going on in the tyre?

Such damage and the effect of speed bumps can put your car’s wheels out of alignment. This in turn causes the car tyres to wear unevenly, even if you don’t feel its effect at the steering wheel. Having wheel alignment checked isn’t too expensive, and is far less costly than new tyres. Have your car’s shock absorbers checked too, and remember that over- or underinflated car tyres cost, the latter in terms of fuel consumption as well as wear.

Looking after your car tyres and its suspension and steering pays dividends in terms of economy, longevity and performance. Should these not be enough of an incentive, there’s that small matter of personal safety too.

Article Resource

Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

The Right Stuff. Which Car Tyres Are The Ones For You?

Car tyres? Pretty much of a muchness, aren’t they? The one-word answer is ‘no’. There are many different kinds of tyre and here are six types used with road cars.

The most commonly-fitted type of car tyre is known as a standard, or all-season tyre. Such tyres are essentially a compromise. They work well enough in both wet and dry conditions, last for a fairly long time and aren’t too noisy on normal road surfaces. A jack of all trades and therefore a master of none? You may think so but in practice, standard car tyres work well for a lot of customers. There are some sub-divisions within this classification. Some car tyres are claimed to give better fuel economy, for example. These nevertheless remain under the ‘standard tyre’ banner.

So, when might you need non-standard tyres? Winter is a good example. Winter tyres come into their own when there’s snow and ice to be tackled. These car tyres have coarse tread patterns, the better to keep the treads clear of snow and ice. Less obviously, they contain rubber compounds and structures that remain flexible at lower temperatures, which enhances performance and roadholding. On the downside, they are noisy and, in normal conditions, wear out faster than standard tyres. For this reason, some people have a set of winter wheels to go with their winter tyres.

A car tyre that performs well in cold weather is totally different from a performance tyre. These, sometimes called ‘summer tyres’, are made of softer compounds, to offer superior grip. As well as having impressive marked speed ratings, such car tyres can cope with the demands of more powerful, faster cars. To do this, they trade wear rate for performance – they don’t last as long as lesser rubberware, and they abhor cold conditions.

As their name implies, run-flat tyres can be used even after suffering a puncture. Such car tyres achieve this with the imposition of a specific distance and speed up to which they can safely be used. Space-saver tyres are a cousin of run-flat tyres. The take up less space in the car but when fitted, must be used with similar restrictions on speed and distance.

What about the still less friendly conditions we might encounter? Enter the all-terrain tyre. For use on such surfaces as gravel and sand, these are particularly tough customers with very bold tread patterns. They have stiffer sidewalls, and the kind of structure that can handle potholes and debris on the road. The car tyre for all seasons? Not really. Sturdy? Yes. Long-lived? Yes? Quiet? Definitely not!

Similarly, mud tyres have an extremely large tread block pattern and are suitable for use only in muddy conditions. Car tyres of this kind are often used on those four-wheel drive vehicles that are actually taken on rough roads; this includes 4×4s that specifically go off-road regularly. The ‘Chelsea Tractor’ that does the school run doesn’t need them.

As should be obvious, the type of tyres you choose depends entirely on the use to which they will be put. Your local Merityre staff will happily give you a professional opinion on what type will be best for your needs.

Article Resource

Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Monday 24 September 2012

Save Money on Fuel by Checking Your Tyre Pressures!


Did you know that having under-inflated tyres affects the handling and grip of your vehicle which can cause it to behave in an irregular or unpredictable way? Furthermore it means that you have a much higher chance of suffering a dangerous blowout, especially on long distance high speed journeys. The tread on your tyres will also wear unevenly if it is over or under inflated and you will need to have them replaced more often.

 By keeping your tyres at the correct pressure your running costs will be reduced as you will save money on fuel. Under inflated tyres require more force to make them turn, and therefore… more fuel.

So… Where do you find the correct tyre pressure for your vehicle? Well there are a number of places to check this. Your vehicle user manual is usually a good place to start as this should also provide information on how much extra pressure you need if you are carrying a heavy load/trailer or if you are going to be travelling at a high speed for a long time.

 Other places it may be are on a label on the front door posts of your car, or on the back of the fuel cap cover. You can also check online at www.tyresafe.org/tyre-safety/tyre-pressure-check.

Now that you know the right pressure for your tyres you need to check that they are correct. To do this you will need some form of tyre pressure gauge like a foot pump or a digital pressure reader (all available at your local car parts store). Remove the dust cover on your valve and attach the gauge.

If your tyres are over inflated…

·         Let some air out by pressing the core of the valve in using a match (or something similar).

·         Deflate the tyre in short bursts and check regularly to ensure you don’t let too much out.

If your tyres are under inflated…

·         Ideally you should inflate your tyres when they are cold as a warm tyre can increase in pressure by 2psi (pounds per square inch).

·         Use a foot pump, plug in a 12v inflator, or use your local fuel stations tyre pressure inflator (these should have charts with all vehicle tyre pressures on them).

Make sure you check all of your tyres, including the spare! Once your tyres are inflated to the correct pressure, put the dust cap back on and you should be ready to go!

At all of our Merityre branches we offer Nitrogen Inflation. By filling your tyres with Nitrogen, they will maintain their correct pressure for longer as Nitrogen doesn’t leak through the tyre’s structure. Normal compressed air consists of mostly oxygen and water vapour, both of which permeate through the tyre casing. By filling your tyres with Nitrogen you will get:

·         Better road holding

·         Longer tread life – up to 25% increase

·         Reduced fuel consumption – Up to 5% reduction

·         No corrosion to the inside of the wheel.
 
You should check your tyre pressures at least once a month, before you go on long journeys, or whenever your vehicle is carrying heavy loads. If you are unsure of anything or would like help, bring your vehicle to your local Merityre branch http://www.merityre.co.uk/find_a_centre.htm and we’ll be happy to do it for you, completely free of charge. 

Thursday 20 September 2012

Checking your tyres… what.. why.. when.. and how…??


WHAT…

So.. How many of you actually know what you’re looking for when you check your tyres? I’ll be the first to admit that before I started working at Merityre I had no idea that the tread on your tyre could wear unevenly, or that you could actually repair a puncture rather than having to buy a brand new tyre. Well in this entry I will try to explain exactly what to look for when you check your tyres.

WHY…

It should go without saying that your tyres are a fundamental part of your vehicle as they are the only parts which have contact with the road (hopefully)!! It is therefore incredibly important that your tyres are in a safe and working condition when driving yourself/friends/family or anyone else around. You never know how many times your tyres may have saved you and your vehicle from serious accidents or damage already.

Did you know that WORN TYRES:

·         Are unsafe

·         Do not give you the adhesion to stay safe on the road

·         Can be illegal… Penalty points here we come

·         Can burst, leading to serious accidents

·         Increase fuel consumption!

·         Pick up foreign objects more easily which can lead to punctures

·         Can lead to other more serious problems with your car

·         Can increase the possibility of prosecution after an accident and increase insurance premiums.

·         Will give you an uncomfortable ride

WHEN…

So firstly, when should you check your tyres? Well there isn’t really a set amount of time between when you should do checks, but we would recommend every week, and before undertaking any long journeys. This means that if you do have any problems, you will spot them quickly and hopefully avoid driving around on potentially dangerous tyres.

HOW…

The first step is to turn on your engine (with the handbrake on and out of gear), and turn the steering wheel so it locks on one side, then turn the engine off again (this will depend if your vehicle has power steering). This allows you to see the full breadth of the tread on your front tyres which is important as it allows you to notice if there is any uneven wear across the tyre.

(Many modern vehicle tyres are very wide and the innermost edge of these can wear right down while the outside edge can appear faultless. This can also occur on tyres if the steering and suspension alignment is out on the vehicle. It is very important to check the full width of the tread!)

LOOK FOR…

·         Now you check your tread depth. The easiest way to do this is using a tread depth gauge, but if you don’t have one of these you can use the tread wear indicators which are located within the grooves of the treaded part of the tyre. These are small raised blocks about 10mm in length and 2mm in height which are situated all around the tyre (so you should be able to find them). The legal limit for tread depth is 1.6mm and the indicators are raised to 1.6mm to 2mm. Therefore if any part of the tread area is running flush with the indicators, your tyre has worn to its lowest level and needs replacing.

 

·         You need to make sure that you check as much of the circumference of the tyre as possible as sometimes one section of the tread will be fine, and another section will be worn. This may mean that the tyre is distorted. You need to check for any material degradation in the tyre, for example cracking and perishing.  At the same time look for any deep or long cuts and any foreign objects. Your car drives over lots of different surfaces so you may see bits of stones here and there, but any object which does not come out easily may have penetrated the tyre and be causing pressure loss (puncture).

 

·         Now have a look at the side walls of the tyres. The side walls are prone to damage from impacts, chafing against curbs, under inflation and tearing. You will be looking for cuts, abrasions or missing rubber. When a tyre has a puncture or has been run under inflated for a while it can cause pinching between the wheel and the road surface (run flat damage). This can be seen as an abrasion mark running the entire circumference and worn letters and numbers on the side walls. When this occurs your tyre will need replacing.

 

·         Bulges can be detected by running the flat of your hand over the entire surface of your sidewall. A bulge represents serious damage to the structural integrity of the tyre.

 

·         In the outer rim of the wheel you will find the valve. Check this carefully for any deterioration of the material. Ensure caps are fitted. By moving the valve stem from side to side, look for cracking of the rubber around the base.

Repeat all of these processes for each tyre and don’t forget the spare!

So, for a quick recap:

Your tyres need attention if they have:

·         Low tread depth

·         Deterioration of the rubber (cracking or perishing)

·         Uneven tread wear (distortion of tyre)

·         Deep cuts or sections of tread missing

·         Embedded foreign objects

·         Side wall damage and bulges

·         Damaged or worn valves

So.. Now you know why it is so important to check your tyres, and not just the tread depth, but the whole tyre. If you find this all a bit too much, then just bring your car to your local Merityre Branch www.merityre.co.uk/find_a_centre.htm and we’ll do it for you absolutely free. We will also give you advice on when you may need new tyres and give you a Merityre Tyre Check Report on their condition. You can also have a FREE Wheel Alignment check which will show up any problems and help to prevent your tyres from wearing unevenly.

For information about our Club Card Plus, go to our website at www.merityre.co.uk or ask at your local branch.

The next entry will explain how to check tyre pressures.

Monday 13 August 2012

Car Tyre Science. Dynamic Performance

Car tyres are often taken for granted. You turn the steering wheel, your car takes the corner, you press the brake, your car stops. This is fine but knowing how car tyres work and the characteristics they generate in terms of handling and roadholding is both interesting and potentially helpful to your driving.

Every car tyre has an area of tread, about the size of an adult’s footprint, in contact with the road surface. This is called, somewhat predictably, its contact patch. Imagine the tyres’ four contact patches travelling along a road in a straight line. These four areas of tread are what keep your car on the road, allowing you to accelerate, steer and brake with confidence.

Now, what happens to car tyres in corners? Imagine the wheels following the arc that the corner represents. The wheels will be following the arc faithfully, but there’s a hidden force at work. Imagine you’re Superman and have X-ray vision. Looking down at the top of a wheel and tyre combination, you’d see that the contact patch will be following a tighter curve than the wheel is following.

So, what’s happening? Why the difference? It’s there because sideways force put on the tyre by the weight of the car is deforming the car tyre’s carcass. Now, imagine a straight line drawn through the centre of the wheel and another drawn through the centre of the contact patch. There will be a difference between the two – this difference is called the slip angle.

As slip angles increase, the car tyre’s grip increases, up to a point. When the forces involved head towards the maximum level of grip the car tyres offer, one of three states will apply. Say the slip angles are equal at both ends of the car. In this case, the grip at each end of the car will be the same. When the grip level’s limit is reached, the car will go into a classic, four-wheel drift. The car’s handling will be ‘neutral’. Racing cars are set up to give neutral handling.

Supposing the slip angles of the car tyres at the front are greater than those at the rear. Then, the driver will need to apply more steering input to make the car follow the chosen curve. This is called ‘understeer’.

When it reaches the limit of effective grip of its car tyres, an understeering car will slide off the track forwards – it simply won’t be able to corner tightly enough. In practice, most road cars understeer. Why? Because understeer is a generally controllable condition – it’ll help scrub off excess speed when a corner is taken too enthusiastically.

The third state occurs when the rear car tyres’ slip angles are greater than those of the front tyres. The rear tyres will be giving less grip than the front ones. At the limit, the car’s tail will slide towards the outside of the curve. When you see a Formula One car or Touring Car spin off a track, it’s gone beyond oversteer.

This explanation is necessarily basic. In fact, very many parameters affect how car tyres respond to the forces imposed upon them. However, the physics are just as basic, and give car designers benchmarks from which to work.

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Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Super Savers. Keeping Car Tyre Costs Down

Depressing as it may be, the tottering economic situation, in this country and across much of the world, is a fact. This means we must live with it but we needn’t merely accept it passively. We can take active steps to keep costs down, and in regard to our motoring and especially our car tyres, there are plenty of tips and tricks for saving money.

Efficiency Counts

The deductive powers of a Sherlock Holmes aren’t needed to figure out where car tyre factors could be costing us money. The key word is ‘efficiency’, and here’s how inefficiency can affect motoring costs.

All cars give a certain power output. Whether this is quoted in kilowatts, pferdestärke or good old horsepower is irrelevant, power can be wasted by inefficiency. A certain amount of power is required to make a car progress, and anything that impedes this progression is wasteful. Under inflated car tyres require more power to make progress, because the lesser tyre pressure increases their rolling resistance. Run your car tyres at the correct pressure, or even a little higher, and you’ll soon see rewards at the fuel pump.

Of course, it isn’t just car tyres that can cause drag, which in turn increases fuel consumption. The current warm weather makes it tempting to use the car’s air conditioning. Would you use it so readily if you knew it could worsen your car’s fuel consumption by up to 11 per cent? You could open some windows, but this creates aerodynamic drag – it seems you can’t win. In fact, it makes sense to cool the car interior by opening the windows at slower speeds. When motoring at 40mph or over, use the aircon – it costs less.

Weight Issues

All car tyres create some drag, that’s also a fact. All car tyres also carry weight, and it’s a fact that the amount they carry can be trimmed, in some cases radically. What you carry on a regular basis in your car depends largely on how you use your car. That said, a lot of people carry unnecessary objects in the car at all times. You could argue that you really need your Wellington boots, snow shovel, overcoat and Thermos flask on board. Well, argue away – you’re carrying what represents dead weight for August and it’s you who are buying the fuel. A combination of ruthlessness and good sense about what lives in the car and when isn’t hard to apply.

Similar thinking should apply to your car’s roof rack or roof box. Sure, it’s well away from your car tyres but what’s on the roof costs you fuel simply by being their. Each has a weight, which you’re paying to transport. Each has a degree of air resistance, even if your roof box has sexy, aerodynamic styling. Again, you’re paying to push that roof-mounted deadweight through the air. Remove it when not in use and your pocket will thank you.

Obvious Strategies

There are a more fuel wasters than car tyre rolling resistance. Driving too hard and/or too fast when you needn’t are money guzzlers, as are speed camera fines and the increased insurance cost of points on your licence. Use the most efficient route, use the highest possible gear and above all, use your head. Everything in this article comes under a single heading, common sense.

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Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Tuesday 10 July 2012

Cat Show. All About A Car Exhaust’s Cleaning Component

On petrol cars, a catalytic convertor has become a standard part of the car exhaust. Catalytic convertors – ‘cats’ for short – originated in America. Like many other items, cats soon went transatlantic and later made their way into European legislation. Unsurprisingly, they wound up in the UK.

Let’s begin with the nuts and bolts of the matter. In chemistry, a ‘catalyst’ is a substance that causes or accelerates a chemical reaction without itself being affected. Fair enough but what has this to do with car exhausts? Still talking at nuts-and-bolts level, a catalytic converter is a device that uses a catalyst to convert three harmful compounds in car exhaust gases into harmless chemicals.

Again, fair enough but what are these three compounds that are so harmful? They are to be found in the exhaust gas of any petrol car and consist of…

Hydrocarbons (incompletely burnt fuel)

Carbon Monoxide (formed when petrol burns)

Nitrogen Oxides (made by combustion heat making atmospheric nitrogen combine with oxygen.)

So, just how scary are these components in car exhaust gases? Carbon Monoxide, a.k.a. CO, is the nastiest one, being poisonous to any organism that breathes air. Nitrogen oxides (NO2) lead to the formation of both smog and acid rain. Relatively innocent Hydrocarbons (HC) just produce smog but are particulate matter, which makes matters worse.

A catalytic convertor, looking rather like a silencer, forms part of a car exhaust system. The catalyst used is liable to consist of precious metals such as rhodium, platinum and palladium. These coat a ceramic honeycomb or ceramic beads inside the ‘cat’. Carbon monoxide is converted into the less harmful carbon dioxide (CO2) and hydrocarbons are converted into carbon dioxide (CO2) and water (H2O). As for the nitrogen oxides, these are converted back into nitrogen and oxygen.

Though they don’t have moving parts, ‘cats’ can suffer malfunctions. If the catalytic convertor in a car exhaust stops working, you won’t necessarily know about this until your next MOT test. A failed cat may just be worn out or its substrate (the metal-coated pellets or ceramic honeycomb inside) may have broken down. Your car may run perfectly well – it just won’t be able to pass the emissions test part of an MOT.

Often, diagnosing what’s awry with the cat in a car exhaust is tricky. If something has gone wrong with the car’s fuel system and it allows raw fuel into the cat, the unit will run red hot. This is usually pretty easy to detect, which is just as well, as the substrate can shatter at such temperatures. Fouled sparking plugs, incorrect ignition timing and failure of the engine’s air pump and/or check valve can also cause overfuelling.

Should the cat’s innards go into meltdown, or shatter through thermal shock or overheating, the result will mimic a blocked car exhaust. A sluggish throttle response is the major clue. Modern electronics mean that a fault light will flash to verify there’s a problem but detecting exactly what the problem is likely to involve diagnostics – on a laptop computer. In any event, should the problem lie within the ‘cat’, a good tyre and exhaust bay will be able to offer you a replacement unit.

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Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Tyres On Trial

Suppose you were regularly wearing out a set of tyres on your Mini Cooper in three miles. You’d certainly be doing something very wrong, wouldn’t you? However, this is the usual car tyre mileage on one of The Russ Swift Mini Display Team’s Coopers and Russ is doing something very right – in the eyes of his sponsors and spectators, that is.

The Team, part of Russ Swift Driving Services, was formed in 1981. Current British Autotest champion and England Autotest Team Captain Russ had often been asked to demonstrate his incredible, tyre-testing car control skills. He realised a gap existed in the marketplace and contrived to fill it.

In 1987, an advertising agency saw a video of Russ at work. This led to the renowned Montego “Car Park” commercial. Though this was aired in the UK for just six weeks, the squeal of tortured car tyres was heard when the performance was featured at the Cannes Film Festival. It was also voted by American judges as the world’s most imaginative car commercial.

Where did Russ go from there? A long, long way. Eight thousand tyre-munching displays in more than 50 countries and three Guinness world records (Parallel parking in the tightest space, J Turn in the tightest space and the fastest donuts) form just a small part of his CV.

Russ and Minis go back a long way too, starting with four British Autotest Championship wins and an International Rally win in Sweden in the early eighties, in a Cooper S. More recently, Russ was involved in promoting the remake of ‘The Italian Job’, performing at premieres in London and New York. He fulfils an advisory role with many police, military, royal and diplomatic drivers, also working closely with RoSPA, the IAM and various other road safety bodies to promote safe driving. A versatile player on the car world’s stage, Russ is committed to ensuring that it is only car tyres that suffer!

The tools of Russ’s trade are largely unmodified cars. Russ uses a Mini Cooper S, standard apart from a “piece of tape on the handbrake button”. Another Mini Cooper has one other mod – a locked differential – to allow for driving on two wheels (this is the one that gets 3 miles per set of tyres – should that be per pair?). Typically, a further Mini Cooper is used (all these are BMW MINIs). Often, an MR RS Mitsubishi Evolution undertakes power slides and donuts.

A typical show features reverse spins at 40mph, parking in a slot between two cars parked side by side, using only the handbrake. Similarly, ‘parallel parking’ involves a handbrake turn into the gap between two cars parked as though at the kerbside. Then there is a ‘dance routine’ to music, involving two cars and a ramp. This last – the ramp – is used for the business of getting the locked-diff Cooper up on two tyres. The show features music and commentary – and audience participation is encouraged. The tyres may be red hot but the invited passengers have been known to end up on the pale side!

Find out more – and see pictures and videos – at www.russswift.co.uk.

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Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Monday 21 May 2012

Buyer Beware: How To Buy A Used Car

For many people, a car is the second most expensive purchase they make. Buying the right car can be easy but it's just as easy to encounter expensive pitfalls, especially when buying used. You need to check on everything, from the car tyres upwards and here are some pointers to help you.

Start by making sure you are looking at the right kind of car for your needs. No matter how much you may want to, you won't fit a family of four in a two-seater sports car. Most people don't make such an obvious error but many buy a car that's too big for their garage, too thirsty for their wallet or too expensive to maintain. All cars have tyres, not all have the ability to be run on a shoestring – and you'll always lose if you have to sell.

Lets assume you've found a car. What next? You have to be certain that the car matches the claims made about it. Checking the VIN (Vehicle Identification Number) is a primary requirement. Does it match the number in the V5 document? If it doesn't or isn't clearly stamped, without any evidence of tampering, the car could be stolen, a 'ringer', or the result of two write-offs welded together.
If the VIN is good, does the history add up? We're talking paperwork here, as well as the state of the car itself. Good car tyres, not to mention shiny paintwork and a ludicrously low mileage are of little value if the mileage figures in the previous MOT certificates don't tally. No MOT certificates? This is your cue to walk away.

Much the same goes for service history, which usually has a record of miles covered in it. If the car has in fact been serviced as it should have been, preferably by an approved dealership, which has entered the details into the service record, the car's beginning to look like a good buy. If every last invoice for what has been spent is present and correct, so much the better. This may include receipts for new tyres, an exhaust, a battery and any accessories.

If buying from a car dealer, a genuine HPI certificate must be provided by law. If buying from a private individual, you can arrange to have an HPI inspection. An HPI check validates the car's history and will reveal any shady elements in its past. Remember that, if buying privately, you will buy a car 'as seen'. This means that you can set tyres to tarmac quite happily but if the engine grenades on the way home, it's your problem. There is no recourse in a private sale.

When looking at the car, be very, very critical indeed. If it has been repaired and the repairs have been professionally done, that's fine. If you see badly-matching paint, poor panel gaps, scuffed tyres and ripply surfaces, the car has been badly repaired. Under the bonnet, look out for oil leaks, corrosion, fluid stains and amateur fixes. Pull out the dipstick and look at the oil. Is it black and treacly? Look elsewhere.

Car tyres can be excellent tell tales, as can the wheels that carry them. Uneven tyre wear suggests suspension misalignment at best, damage at worst. Tyres with 3 millimetres or less of tread need replacing, which won't cost the seller a penny. The same goes for cracked tyres or ones with lumps or bulges. Alloy wheels that have been badly kerbed will show significant damage, and say a lot about how the car has been driven.

Finally, remember these golden rules. One: you can always find a rival example of the car you're examining. Two: it’s a buyer’s market; you can always walk away. Three: always buy with your head, rather than your heart!

Article Resource

Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

What Are Car Tyres Made Of?

We're told, not necessarily reliably, what little girls and little boys are made of. Happily, we can learn with accuracy what car tyres are made of, and it's reassuring to know that the flexible friends that let our cars be steered and stopped unfailingly are so well constructed.

The heart of a car tyre is an inner liner made of halobutyl rubber. This includes additives that promote air retention. The inner liner is clad in a three-layer body ply, consisting of a layer of Rayon, Nylon, Polyester or Kevlar sandwiched between two layers of rubber. Car tyres may have one or two body plies, giving structural strength and flexibility.

We now move on to visible structures in our car tyre. Using materials that include antioxidants and antiozonants lets car tyre sidewalls resist abrasion and chemical attack, while promoting flexibility and strength.

The inner edges of the sidewalls are the car tyre's beads. Made of corrosion-resistant copper or brass-coated high tensile steel wire moulded into rubber casings, the beads are a strong point, holding the car tyre to the wheel and keeping air sealed inside. The triangular-section area joining the bead and the sidewall is the apex, the cushion between the two.

Back under the skin of the car tyre, beneath the tread, lies the belt package. Two layers of rubber sandwich a layer of steel cords. This package is what allows the car tyre to handle road impacts, from potholes, stones and so on. Usually the cords run radially within the belt package, hence the name 'radial tyre'. The visible tread and the layers beneath it are made of rubber compounds with a specific degree of hardness. Harder compounds wear well, softer compounds offer better grip; a compromise between the two is usually offered.

Now we know what car tyres are made of, how do we go about building one? In short, we don't, unless we happen to own a car tyre factory. In such a premises, a tyre's inner liner, body plies, sidewalls and beads are first assembled around a special drum. After the belt package and tread are added, the components are spliced together before the tyre is automatically inflated and shaped. At this stage, the tyre is uncured, or 'green'.

In this green form, the car tyre's parts are yet to be bonded together, in a curing process. A rubber bladder, inflated inside the car tyre with hot water, steam or an inert gas, forces it into a mould. The 350-degrees Fahrenheit temperature and 350psi pressure used speed up chemical reactions in the car tyre carcass, and the curing process takes about 15 minutes.

The cured car tyre is run on a mock tarmac surface, to highlight any localized inflexibility and/or unbalanced sections. While all tyres are visually inspected, a random sample of tyres is also X-rayed.

Heavy-duty equipment and extremes of pressure and temperature are used make a car tyre. It's comforting to know that these things combine to produce a tough, long lasting result.

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Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Monday 23 April 2012

Extreme Tyres. Car Tyres And More, Small And Large

Sometimes, size is all that matters. It's important when choosing car tyres to select ones that are the right size. However, if you think the 205/45 x 17 tyres on your Mini Cooper S are rather special, stand by to be amazed, and not a little outclassed.

In this instance, 205 millimetres equates to 8.07 inches. These car tyres may look wide on a Cooper S but in reality, they aren't much to write home about. The world's widest car tyre, on the other hand, is worth describing in a letter. The Pirelli P Zero Nero 405/25 ZR 24 is an asymmetric car tyre aimed at 'tuners and the most demanding sports performance drivers'. With a 25% aspect ratio, as the numbers say, this car tyre is bound to look wide. With a width of nearly sixteen inches, it is wide – extremely wide. In fact, the widest car tyre on Pirelli's website is a mere 315 section item, which equates to a comparatively paltry 12.4 inches. That said, the web reports a Chevrolet Corvette special sitting on 405-section tyres, on 24 x 15-inch wheels…and there are pictures to prove it.

To go still bigger as regards tyres, we must move out of the realm of car tyres. Bridgestone used to hold the record for making the world's largest production tyre, with its 59/80R63 V-Steel E-Lug S tyre. Fitted to earthmovers such as the Caterpillar 797B and 797F, these tyres stand 4.02 metres high – that's a little under thirteen and a quarter feet. Each earthmover wears six of these tyres.

Feeling your car tyres are a little underwhelming sizewise? There's more to come. The 63-inch OTR (Off-The-Road) tyres made by Titan are nearly fourteen feet tall and weigh a staggering 12,500 pounds apiece. Each tyre has a nominal load rating of a whopping 101 tonnes. Just don't expect your trusty tyre fitter to stock these 57.9 inch-wide Titan 59/80R63 tyres. Their size and their 5.66 tonne weight means the tyre racks probably won't cope.

Now that you're feeling distinctly ill-equipped with your pathetic little car tyres, the balance can be redressed with the aid of the 'Wind-Up'. This, the world's smallest road legal car, was built by British inventor Perry Watkins. Being a tiny car, the Wind-Up has tiny car tyres, which we'll come to in a moment.

Let's first see the vital statistics that demand such tiny car tyres. The Wind-Up is 41 inches tall, 51 inches long and 26 inches wide. Its Shanghai Shenke quad bike chassis is powered by a 150cc engine with continuously variable transmission. This gives the Wind-Up a top speed of 40mph, and a frugal thirst – it takes 70 miles to sip a gallon of fuel.

The Wind-Up's tyres come from small motorbikes. At the rear, it wears the wheels and tyres from a Honda Monkey Bike, the tyres being dinky 3.5 x 8-inch items. At the front, the Wind-Up rides on tyres from a 1939 Brockhouse Corgi paratrooper’s mini motorcycle, also 8-inch items.

Should you encounter a set of the miniscule car tyres that support the Wind-Up, there may be something more than a little familiar about the vehicle. Its 31.4 cubic foot body was sourced from a coin-operated ride favoured by little kids. Yes, Postman Pat's van got a new lease of life, courtesy of Perry Watkins.

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Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

The Point Of No Return. Why Car Tyres Fail

Car tyres can fail for a variety of reasons. Some are more common than others but all are avoidable with a little foresight. So, let's look at some problems that can cause tyre failure, and learn how to avoid them.

Underinflation

Running your car tyres at too low a pressure has an immediate penalty. Underinflated tyres have higher rolling resistance than tyres running at the correct pressure. This means you waste fuel on pushing the tyres along the road. A less immediate but more punishing penalty comes from the same lack of pounds per square inch of air pressure inside the car tyre. Put simply, underinflated tyres can overheat. If the tyres overheat enough, it's bye-bye tread or tyre carcass – i.e. it's blowout time.
Inflating your car tyres correctly, to the pressure the car and/or tyre manufacturer recommends, is simple enough, and far less costly than new tyres or a spectacular blowout.

Overinflation

Given the above, it may seem logical to run your car tyres at a pressure higher than the one recommended. Wrong! Tyres running at too high a pressure lose compliance. Meaning? They can't cope well with road irregularities and will be more easily damaged. Such damage can occur deep within the tyre carcass and lead to a dramatic high-speed failure. Once again, the solution is to keep your tyres inflated to the correct pressure.

Excessive Speed

If you've saved a few pounds by buying car tyres that are under specified for your car's capabilities, there's no profit in preening yourself about it. Car tyres have a speed rating, denoted by a letter on the sidewall, for a reason. More highly-rated tyres have superior internal structures and can lose heat more efficiently than lesser items.
While your insurance company will take a very dim view of your running on inappropriate tyres, worse things can happen. Under specified tyres can fail, especially in hot conditions.
A good tyre bay will advise you on which speed rating is right for your car. Take the advice: always buy the right tyres.

Overloading

Car tyres carry a load rating as well as a speed rating and this too is with good reason. While overloading may not often affect passenger cars (except perhaps those used for towing), bigger vehicles can be seen wearing underrated tyres. This goes for 4x4s as well as pick up trucks and small to medium-sized vans.
Once again, a tyre bay is the source of knowledge – if in doubt, have your current tyres checked.

Road Hazards

Which road hazards? Good question, given the road offers plenty of hazards. Those particularly affecting car tyre integrity are pot holes, debris and kerbs. Hit any of these with any severity and you may damage a wheel, as well as a tyre. However, impact damage, even at parking speeds, can wreak unseen havoc within a car tyre.
When checking your car tyre pressures, look out for cuts, lumps and bulges – all can be harbingers of structural disaster in a tyre.

Excessive Wear

In these financially demanding times, it's understandable for drivers to try wringing the maximum life out of their car tyres. That said, taking a car tyre down to, or even past, the tread wear indicators moulded into its treads is false economy, not to mention dangerous.
This is another thing to check when you get down and personal with your car tyres. Remember that well worn tyres can lack structural strength as well as grip.

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Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Wednesday 7 March 2012

Flat Lines. How To Change a Car Tyre Safely

A car tyre must be inflated to work properly. Should you suffer a puncture, you can change the wheel concerned. Here's how to do so in safety…

When

When to change a wheel becomes pretty obvious. A heavy pulling at the steering wheel and/or squirmy handling with assorted noises is usually sufficient to let you know a car tyre has deflated.

Where

Where to undertake a tyre change may seem obvious but this isn't necessarily so. The first and most important rule is to never, ever try to change a car tyre by a busy carriageway, be it a on a motorway hard shoulder or at the side of an A-road. Why? Quite simply, it is hugely unsafe.
So, what if you're caught out, on a busy road? Sometimes, it's possible to coax your car to a quieter location. Bear in mind that you'll need to find a level, firm surface to work on. If the car tyre has deflated fully, just pull up and call out the cavalry. The breakdown service will do the rest, after your mobile phone, or a roadside phone, has done its lifesaving bit.

How to prepare

A spot of preparation makes changing a flat car tyre much easier. Pull up in your chosen spot, apply the car's handbrake, put the car into gear (or 'park'), switch on the hazard lights and set up the car's warning triangle. This should be placed 45 metres (147 feet) behind the car.
The next stage in dealing with a flat car tyre is to have any passengers leave the car and stand well away from it, and from passing traffic. Then, it's time to extract the spare wheel, jack and tools – your car's handbook will tell you where they are to be found.

Jacking the Car

This step in the proceedings involves safety procedures, to which you must pay attention. First, you have to chock the wheel diagonally opposite to the one with the flat car tyre. No chock to hand? Then find a stone, brick or any other piece of debris that'll do the job.
Time for your car to go up in the world. There'll be a specific place under which the car jack must be placed. Once again, the handbook will tell you where this is. Do not improvise; only the proper jacking point will do. With the jack placed correctly, wind it up until it's bearing enough of the car's weight to not move.
Loosening the wheel nuts or bolts holding the wheel with the flat tyre comes next. These are always undone anticlockwise, with the wheelbrace that is in the toolkit. You may have to undo a locking wheel nut too – there's a key device for that.
Now, wheel fastenings can be very tight. Use the wheel brace so you'll be applying downward pressure (far less injurious if the tool slips). Loosen the fastenings first; the wheel can't turn because it's still on the ground.
Now, you can jack the car up. Do this steadily, until there is daylight between the flat car tyre and the roadside surface.

Changing the Wheel

Unscrew the fastenings completely one by one, removing the uppermost one last. You may need to 'persuade' the offending wheel to come off but be careful – over enthusiasm could cause the car to fall. For this reason, never let any part of you go between the car and the ground.
A car tyre and wheel combination can be heavy. Make sure that when lifting one, you’re on a firm footing with a straight back. Fit the spare wheel, securing it with the topmost fastening. Then, refit the remaining fastenings, tightening them only enough to seat the wheel firmly on the hub. Lower the car until the tyre is on the ground, and tighten the fastenings in a diagonal pattern. Now, you can stow the deflated wheel and tyre, put your tools away and continue your journey.

Finished?

Not quite, there are a couple of post-wheel change necessities. You need to get to a tyre bay, to have the wheel tightened to a specific torque – a repair on the flat car tyre is often possible. If you need to continue on the spare, you have to be sure that the car tyre on the spare wheel you've used is at the correct pressure. Finally, if the spare tyre is a space saver, there'll be limitations concerning speed and distance. The car handbook will show you what applies.

Article Resource

Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Under Control. How Computers Help Car Tyres

'If in doubt, blame the computer' is an office standby. When it comes to car tyres, there are plenty of instances when it would be appropriate to say, 'Thank the computer'. Several computer-controlled systems optimize car tyre performance these days. Let's pick our way through the acronyms and look at some such systems.

ABS a.k.a. the Anti-Lock Braking System has its roots in aircraft technology. Gabriel Voisin, a French aeronautical and automotive engineer came up with it as far back as 1929. Forty-two years later, 'Sure Brake' appeared on the 1971 Chrysler Imperial. It's now hard to find a single car tyre whose stopping power isn't maximised by ABS. Here's how it works.

Enter the ECU, or Electronic Control Unit, which is what is in charge of ABS. Imagine a car tyre is rotating more slowly than its fellows. A wheel speed sensor detects this, and tells the ECU. The ECU, in turn, opens a hydraulic valve to divert brake fluid pressure away from the locking wheel, until the tyre in question speeds up again. The system can do this at up to 20 times per second. The result? On a wheel that isn't quite locking, the car tyre is gripping at maximum efficiency. A locked wheel offers virtually no grip, while a wheel nearly at locking point can still offer steering and braking force.

EBD (or EBFD) is a refinement of ABS. This acronym stands for Electronic Brake Force Distribution. On the old, 'classic' Mini, for example, there used to be a mechanical inertia valve, which would reduce braking force to stop the rear tyres locking under heavy braking. EBD does the same thing, far faster, far more accurately and in relation to each car tyre simultaneously.

Strange as it may sound, ABS can help a car tyre achieve maximum traction under acceleration. TCS – the Traction Control System – uses the ABS's wheel speed sensors to detect if a car tyre on a driven wheel is spinning (i.e. not gripping). The TCS applies braking force to the spinning wheel for a few milliseconds. In more sophisticated TCS systems, the throttle can be cut briefly, preventing wheel spin.

Speaking of sophisticated systems, we can now look at ESC (Electronic Stability Control). This again is ABS-related. In ESC (or DSC – Dynamic Stability Control), two further sensors play a role. One detects the angle of the steering wheel, while its gyroscopic stablemate checks this angle against the car's direction of travel. Should the figures not add up, the system applies braking force to individual wheels. Once again, each car tyre is maintained at its optimum level of efficiency in any given circumstance, by the application of very short pulses of braking pressure, and/or throttle input, as appropriate.

Here's where further refinement steps in, and where we become awash with acronyms. It's probably best to think of the refinements under the ACC (Adaptive Chassis Control) banner. Often using a button, with markings such as 'Comfort', 'Sport' and even 'Race', a car driver can dial in all manner of changes to how his car responds. While the stiffness of physical springs can't be changed electronically, the firmness of the suspension can, by the actuation of electronic tweaks to suspension damper rates. While the car tyres don't change, that which controls them can. It's possible for driving force to be distributed according to car tyre grip across an axle and, in some cases, between the front and rear wheels.

The bottom line about these immensely clever, capable systems is that they use car tyre grip as a benchmark. When the car tyres are offering optimum grip, tyre performance – and therefore the performance of the car – is necessarily optimized.

Article Resource

Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Thursday 9 February 2012

Tell Tale Tyres. What Wear Patterns Mean

Car tyre forensics seems like an odd concept. However, in many instances, a 'dead' tyre can give you as much information as a corpse in the hands of a police pathologist. Information? Yes, tell-tale signs that can tell you what caused the tyre's untimely demise. Such information is useful because in indicating possible faults, it can tell you what might require fixing to give your replacement car tyres or tyre the maximum possible life.

Let's start with the basics. The type of tyre wear pattern that's to be expected is straightforward, and is characterised by the tread's having been worn away to the extent that the tyres’ tread wear indicators are at or near level with the surface of the tread. So, the tyre has nearly finished its useful service life. Is this the end of the story? Not necessarily. The suspension geometry on some cars can mean that the tyres' treads don't necessarily wear completely evenly.

Other car tyre tread wear patterns tell a different tale. What must be borne in mind is that they don't necessarily tell it quickly – some wear conditions take a while to show that something is awry. For example, what does feathering on both outer edges of the tyre tread suggest? This pattern is the most likely indicator that the tyre has been consistently run at too low a pressure. Conversely, a strip worn around the centre of the tread indicates a tyre having been run at too high a pressure.

What about feathering on one edge of the car tyre tread? Should such wear be on the outer edge of the tyre, it suggests that the car's steering is misaligned, having too much toe-in. Similarly, feathering on the tread's inner edge indicates that there is too much toe-out. This kind of wear usually appears on both front tyres, as the steering will generally attempt to run straight and true. The fact that the steering tries to compensate for misalignment by effectively evening out the wear on each side of the car is no compensation in itself. However, it does advise you to have the wheel alignment checked before your new tyres suffer.

It's worth noting that feathering on one side of a car tyre tread occurring only on one side of the car indicates something other than misaligned wheels. In this instance, one-sided feathering is more suggestive of wear in the car's suspension joints, its springs and/or its wheel bearings. This pattern can also occur when the wheel's camber, its position in relation to the vertical plane, is incorrect. Camber change of this kind can be caused by wear in the aforementioned areas; damage to the suspension can cause the same problem.

'Cupping' is also a phenomenon that can show you something is amiss on your car. A tread with cupping (also called 'dipping' or 'scalloping') has patches of wear across its tread's surface. This can look almost like the tread surface has softened in places, or has been scooped away. Cupping indicates one of two problems or a combination of them. Wheels significantly out of balance can suffer cupping, as can car tyres under the control of worn shock absorbers. Cupping can affect rear tyres but it's more commonly seen on a car's front tyres.

As you can see, car tyre tread wear can be the result of maladjustment but wear and damage can give similar results. In the interests of your wallet, if not your life, pay attention to what your car tyres are telling you.

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Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Star Cars. More Objects of Desire On Tyres

We may not view them for very long but movie star cars live on in our memories. Not all movies featuring memorable motors are car chases wrapped in sub-plots. That said, car tyres aren't just for these four-wheeled screen idols to sit on. Yes, rubber was burnt in many instances. The tyre-smoking heroes here have one thing in common – they're all from the 'States. So let's take a look across the pond at some US-born petrol-driven thespians.

The 1971 film 'Vanishing Point' is a classic car chase wrapped in celluloid. Starring Barry Newman and Cleavon Little (who went on to great things in 'Blazing Saddles'), Vanishing Point revolves around a fifteen-hour, transcontinental drive from Denver to San Francisco. The star car tyres doing the revolving in the film were fitted to a 1970 Dodge Challenger R/T, the suffix letters referring to 'road and track'. This 6.2-litre monster, driven by Erich Heuschele, developed the power of 375 gutsy, all-American horses. The car's F70x14 car tyres put the power onto the tarmac, with the aid of the Challenger's R/T package. Interestingly, the same model in the same colour popped up in Quentin Tarantino's 2007 movie 'Death Proof'. What's more, the Challenger's pedigree goes back in time. The black car driven by the baddies in 'Bullitt' was a 1968 Dodge Challenger 440 R/T.

More tyre-smoking Detroit iron finished in black starred in 1977's 'Smokey and the Bandit'. The motorised matinee idol here wasn't Burt Reynolds, it was a 1977 Pontiac Trans Am. This car's history can be traced – it stemmed from a General Motors Design show car created for GM design supremo Bill Mitchell. On this Trans Am, the car tyres were put under pressure in more than the literal sense. The car's 7.5 litre V8 motor became the last of the muscle car engines. Increasingly stringent emissions regulations in the US finally killed off these big V8 beasts in 1980. The stunt team on 'Smokey' pre-empted this, killing off, or at least damaging, all five film cars.

Now for something more unusual, though still in black paint. The next movie star was built using three Model T Ford bodies and a 133-inch hand made chassis. The Munsters Koach was created in 21 days in 1964, at a cost of $18,000; it took 500 hours to make its ornate steel scrollwork alone. Another big V8, by Ford this time, sent the power to the tyres via a four-speed manual gearbox, and the brass radiator and wings were hand formed. The Koach had ten Stromberg carburettors. On an eight cylinder engine? Not really. The visible carburettors were dummies, concealing two functioning four-barrel carbs.

In the Munsters, Grandpa, played by Al Lewis, became more than a little jealous of the Koach. So he acquired 'Drag-U-La'. This vehicle was notable for its spindly front tyres, mounted on Speedsport English buggy wire wheels. The V8 engine's 350 horsepower was transmitted to 11 inch-wide Firestone racing slick car tyres, mounted on specially made ten-inch deep Reynolds aluminum Rader drag wheels. Still more characteristic for a 'vampire', Drag-U-La's body shell was a coffin. The original Drag-U-La, one of four built, hangs from the ceiling in Planet Hollywood, Atlantic City, New Jersey.

Who was the talented creator of these last two oddities? The man responsible for putting a lot of tremendously memorable tinseltown tin on tyres. Yes, it was none other than Batmobile creator George Barris

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Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.