What do you know about your tires? – Tire information series
Treadwear, Traction, Temperature
It isn’t just size that matters when choosing tires for your vehicle. There are some other numbers and letters on the side of the tire that you should pay attention to. You will find the treadwear listed in three digit numeric format such as “320” and the traction and temperature in letters such as AA, A, B, or C.
The treadwear rating is a relative measurement of the tire’s durability and tread life. It is important to remember that road surfaces, driving habits, and other factors determine actual tread life. Each tire manufacturer independently determines treadwear through their own tests. Treadwear is not based on any one industry or government standard. The higher the number the longer the tire should last compared to similar tires from the same manufacture with lower numbers. A tire with a treadwear rating of 800 should theoretically last about twice as long as a tire with a treadwear rating of 400. A longer life tire will be designed with a harder rubber compound to withstand wear better.
Unfortunately, while a harder compound tire will last longer it will do so at the expense of some traction – particularly on wet surfaces. The softer tire compounds will grip the road surface better for improved handling and braking performance. The traction specification is listed beside the treadwear in the form of letters such as AA, or A, or B with AA being the highest grade possible. The traction rating is a measurement of a tire’s ability to stop on a straight, wet surface under controlled conditions. It does not indicate the tire’s cornering ability on a wet surface or its traction on ice or snow.
The temperature rating is a measurement of a tire’s resistance to heat generation under normal operating conditions at recommended inflation pressures. Temperature grades range from A to C, with A being highest rated and therefore most resistant to heat generation. Tires graded A effectively dissipate heat up to a maximum speed that is greater than 115 mph. B rates at a maximum between 100 mph and 115 mph. C rates at a maximum of between 85 mph to 100 mph. Tires that cannot grade up to C or higher cannot be sold in the US.