All car tyres have them but not everyone knows what the markings moulded in a tyre's sidewall means. At the very least, it is necessary on many cars to check the sidewall as the tyre pressure to be used can relate to the tyre size. However, this little trip through the meaning of the markings will inform, especially when the time to buy new tyres arrives.
Here, we can use a theoretical, typical car tyre. Let's say it's marked 185/55R13 91 H. Confused already? Don't be, things will become perfectly clear! Take the tyre markings one by one….
185 – This is the width of the tyre’s section in millimetres, i.e. the width of the carcass of the tyre, not its tread's width. 185 millimetres is a little over seven and a quarter inches.
55 – This figure refers to the tyre’s aspect ratio, which is the height of the tyre height expressed as a percentage of its width. 55 is a low-ish profile but aspect ratios can go as low as 30%. Low profile car tyres grip well and deform little but the cost is reduced ride comfort and poor protection against potholes, kerbs and road debris.
R – This couldn't be simpler. Here, R means radial.
13 – This number refers to the diameter of wheel the tyre will fit. Why this is expressed in inches rather than millimetres isn't clear but it is standard practice.
91 – This is the tyre load index, a code for the maximum load capacity of the tyre when driven at its maximum rated speed. The figure 91 means a rating of 615 kilograms.
H – This final marking shows the tyre’s speed rating. This H rating means the tyre can cope with extended use at a maximum speed of 130 miles per hour (210 kilometres per hour). The highest possible speed rating is Z. Car tyres thus marked are capable of maintaining 150 mph (240 kph).
There are numerous other markings on a car tyre's sidewall, some of which are for the tyre fitter's information. For example, if the tyre has a specific direction of rotation, there will be an arrow. A 'TWI' marking denotes where the tread wear indicator(s) are moulded into the tyre's tread. A coloured dot will show the tyre fitter where the tyre casing should sit on the wheel in relation to the valve. There will also be ECE (not EEC) type approval markings, possibly special construction markings, such as M&S (Mud and Snow), and a maximum pressure marking.
One marking that could be of interest to you is the DOT code. The last four numbers in this show the tyre’s date of manufacture. Four-digit codes began after 2003 so if your new car tyre has the code 2 5 0 9, it was made in the 30th week of 2009. Tyres over 6 years old must never be used.
All very interesting but do these markings matter to you? Apart from the aforementioned tyre size vs. tyre pressure element, the speed and load ratings are extremely important. Why? Because at best, using under-specified tyres is illegal and can invalidate your car insurance. At worst, the wrong kind of tyre can fail and cause a potentially lethal accident at high speed.
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, 7 November 2011
Winter of Discontent…Beat it with Winter Tyres
Last night's frost warning was a harbinger of the approach of winter. Here in the UK, we should be used to harsh conditions. However, give us an inch (of snow) and the miles aren't covered…the country tends to come to a grinding halt. Is there a solution? Well, the increasingly popular winter car tyres may help.
This begs a question: are winter tyres genuinely useful or are they just a way of extracting more money from we motorists? Let's see.
Recommended in Andorra, Italy, Norway and Switzerland, winter tyres are compulsory in Austria, Germany and Sweden and mandatory in Finland. These rules naturally apply on snow-covered roads and/or during the snow season. Often, there is the distinction that the tyres must be marked 'M&S' (no, not Marks and Spencer, the marking stands for 'Mud and Snow'.) Newer snow tyres may have a symbol of a snowflake in front of a mountain. Currently, the distinction between winter and snow tyres is a touch unclear. A good tyre bay will advise you of the exact designation and specification.
In fact, specification is what winter tyres are all about. Car tyres in general are made in much the same way but the rubber compounds used and the tread patterns vary. Winter tyres are made with a high silica content. The probable tread pattern has two tricks up its sleeve. One is a more aggressive tread pattern than 'summer' car tyres. This is present to enhance grip.
The winter car tyre tread's second line of defence involves a winter tyre key word, flexibility. When ordinary tyres have to work in temperatures below 7 degrees centigrade, they stiffen up in the cold conditions. In winter tyres, the compound and tread pattern both improve flexibility.
The benefit of winter tyres is that they give better grip in cold conditions, in rain as well as when snow and ice are about. There are plenty of subjective reports concerning car tyres and most of those concerning winter tyres are favourable. In some cases, cars found to be pretty hopeless in snow are transformed!
Are winter tyres the car tyres for all seasons? Their name offers a huge clue here. Summer tyres will outperform winter ones on dry roads and in reasonable temperatures, and winter tyres, having a softer compound, will naturally wear faster. This suggests following the lead of many continental drivers. They have two sets of tyres, one for winter, one for summer.
This brings us, in turn, to a potentially superior arrangement, which is also popular on the continent and in some cases is a legal requirement. Generally speaking, car tyres can handle most road conditions. However, in the depths of winter, the environment down at road level can be especially harsh. Car tyres may be able to cope with the salt and grit that gives some winter grip but our alloy wheels can suffer. Many popular cars have base models that wear steel wheels. One solution is to have a set of winter tyres on these. A set of steel wheels, with winter tyres, balanced and ready to roll can be fitted when the thermometer starts to plummet. With these 'winter wheels' fitted, your car can take on whatever the season has to throw at it, while your pristine summer wheels can live in cool, dark storage, ready for Spring. Bear in mind that suitable wheel nuts/bolts will have to be factored into the equation.
What's the bottom line? Assuming you need to use your car in the off season, winter car tyres are worth the investment.
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.
This begs a question: are winter tyres genuinely useful or are they just a way of extracting more money from we motorists? Let's see.
Recommended in Andorra, Italy, Norway and Switzerland, winter tyres are compulsory in Austria, Germany and Sweden and mandatory in Finland. These rules naturally apply on snow-covered roads and/or during the snow season. Often, there is the distinction that the tyres must be marked 'M&S' (no, not Marks and Spencer, the marking stands for 'Mud and Snow'.) Newer snow tyres may have a symbol of a snowflake in front of a mountain. Currently, the distinction between winter and snow tyres is a touch unclear. A good tyre bay will advise you of the exact designation and specification.
In fact, specification is what winter tyres are all about. Car tyres in general are made in much the same way but the rubber compounds used and the tread patterns vary. Winter tyres are made with a high silica content. The probable tread pattern has two tricks up its sleeve. One is a more aggressive tread pattern than 'summer' car tyres. This is present to enhance grip.
The winter car tyre tread's second line of defence involves a winter tyre key word, flexibility. When ordinary tyres have to work in temperatures below 7 degrees centigrade, they stiffen up in the cold conditions. In winter tyres, the compound and tread pattern both improve flexibility.
The benefit of winter tyres is that they give better grip in cold conditions, in rain as well as when snow and ice are about. There are plenty of subjective reports concerning car tyres and most of those concerning winter tyres are favourable. In some cases, cars found to be pretty hopeless in snow are transformed!
Are winter tyres the car tyres for all seasons? Their name offers a huge clue here. Summer tyres will outperform winter ones on dry roads and in reasonable temperatures, and winter tyres, having a softer compound, will naturally wear faster. This suggests following the lead of many continental drivers. They have two sets of tyres, one for winter, one for summer.
This brings us, in turn, to a potentially superior arrangement, which is also popular on the continent and in some cases is a legal requirement. Generally speaking, car tyres can handle most road conditions. However, in the depths of winter, the environment down at road level can be especially harsh. Car tyres may be able to cope with the salt and grit that gives some winter grip but our alloy wheels can suffer. Many popular cars have base models that wear steel wheels. One solution is to have a set of winter tyres on these. A set of steel wheels, with winter tyres, balanced and ready to roll can be fitted when the thermometer starts to plummet. With these 'winter wheels' fitted, your car can take on whatever the season has to throw at it, while your pristine summer wheels can live in cool, dark storage, ready for Spring. Bear in mind that suitable wheel nuts/bolts will have to be factored into the equation.
What's the bottom line? Assuming you need to use your car in the off season, winter car tyres are worth the investment.
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.
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