Tires: Application and ID

TIRE IDENTIFICATION





Tire type, size, aspect ratio and speed rating are encoded in the letters and numbers imprinted on the side wall of the tire (e.g. 275/35 ZR 18). Refer to the chart to decipher the tire identification code.
Performance tires will have a speed rating letter after the aspect ratio number. The speed rating is not always printed on the tire sidewall. The letter "Z" indicates that the tire is speed rated for continuous speeds of over 149 mph (238 km/h).
- Q - up to 100 mph
- T - up to 118 mph
- U - up to 124 mph
- H - up to 130 mph
- V- up to 149 mph
- Z - up to and over 149 mph (consult the tire manufacturer for the specific speed rating)

TIRE RATING
The tread wear/traction/heat (temperature) resistance ratings are also imprinted on the tire sidewall (e.g., 250 AB).
The tread wear rating is expressed as a 3-digit number. It is a comparative value based on the wear rate of a tire when tested under controlled conditions. The test is done on a U.S. Government designated test course. For example, a tire with a tread wear rating of 300 should have a 50 percent better tread life than a tire with a 150 rating. In reality, the tread wear performance of the various tires greatly depends upon:
- The driving habits of the owner
- The actual driving conditions
- Tire service attention
- Climate
- Road surface temperature
- The road/street surfaces that the tires encounter
The tire traction and the heat (temperature) resistance ratings follow the tread wear rating. They are encoded either "AA," "A," "B" or "C." An "AA" code represents the best rating in either category.
The traction ratings are based upon a tires's ability to stop a vehicle on wet pavement when tested under controlled conditions on U.S. Government designated asphalt and concrete test surfaces. The traction rating assigned to a specific tire is based on straight ahead braking traction tests and does not include cornering/turning traction.
The heat rating represents a tire's resistance to temperature increases from friction and its ability to dissipate heat. This test is done under controlled conditions on a specified indoor laboratory test wheel. Sustained high temperature can cause the construction material of a tire to degenerate. This will greatly reduce the life of the tire. A "C" rating represents the minimum acceptable heat resistance performance for a tire.

NOTE: The heat resistance rating is based on the tire being properly inflated and not overloaded. Excessive speed, under-inflation and/or excessive load can cause the temperature of a tire to increase above normal. This excessive heat may cause tire failure.