Tyre Talk
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After media reports recently highlighted certain coding on the sidewall of tyres, Customer Engineering Manager, Alan Sutton helps clarify what the numbers mean and what reliance we should place on them. Every modern tyre has markings on the tyre wall. These markings are a series of numbers and codes, used internationally, and exist for the identification of tyre structures, dimensions and applications. The illustration (right) gives an example of the markings as they appear on a passenger tyre: A tyre’s age
can be found out from the U.S. Department of Transportation (DOT)
coding located on its sidewall. The last numbers on the DOT donate
the week and year of construction. The full DOT is only on one side
of the Service life is dependent on many variables such as driving conditions, vehicle loads, inflation pressure, and general maintenance or abuse of the tyre. There is not a specific age at which tyres have to be replaced. Much can depend on how the tyre has been exposed to the elements, stored, either on or off the vehicle and in general treated. The last thought though is if you are ever in doubt of the condition of the tyre (especially if it is showing signs of weathering) replace it. The DOT though National Highway Traffic Safety Administration’s (NHTSA) also has Uniform Tire Quality Grade Standards (UTQG) |
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| UTQG grading is required by US law for most passenger car tyres sold in the United States (not deep treaded light truck tyres). There are three grading categories: Traction / Tread wear / Heat. These are branded on the tyre’s upper sidewall. | |
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July 2008 |