Tire Quality Grading
Uniform Tire Quality Grading and TPC LabelQuality grades can be found where applicable on the tire sidewall between tread shoulder and maximum section width. For example:
Treadwear 200 / Traction AA / Temperature A
The following information relates to the system
developed by the United States National Highway Traffic Safety Administration (NHTSA),
which grades tires by treadwear, traction, and temperature performance. This applies only to
vehicles sold in the United States. The grades are molded on the sidewalls of most
passenger car tires. The Uniform Tire Quality Grading (UTQG) system does not apply to
deep tread, winter-type snow tires, space-saver, or temporary use spare tires, tires with
nominal rim diameters of 10 to 12 inches (25 to 30 cm), or to some limited-production tires.
While the tires available on new passenger cars and light trucks may vary with respect to these grades, they must also conform to federal safety requirements and additional General Motors Tire Performance Criteria (TPC) standards. All Passenger Car Tires Must Conform to Federal Safety Requirements In Addition To These Grades.
Tire Treadwear
The treadwear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test course.
If your tires have an all-season tread design, the TPC number will be followed by an MS (for mud and snow).If you ever replace your tires with those not having a TPC Spec number, make sure they are the same size, load range, speed rating and construction type (bias, bias-belted or radial) as your original tires.
For example, a tire graded 150 would wear one and a half times as well on the government road course as a tire graded 100. The relative performance of tires depends upon the actual conditions of their use, however, and may depart significantly from the norm due to variations in driving habits, service practices and differences in road characteristics and climate.
Tire Traction
AA, A, B, C
The traction grades, from highest to lowest, are AA, A, B, and C. Those grades represent the
tire's ability to stop on wet pavement as measured under controlled conditions on specified
government test surfaces of asphalt and concrete. A tire marked C may have poor traction
performance.
Warning: The traction grade assigned to this tire is based on straight-ahead braking traction
tests, and does not include acceleration, cornering, hydroplaning, or peak traction
characteristics.
Tire Temperature
A, B, C
The temperature grades are A (the highest), B, and C,
representing the tire's resistance to the generation of heat and its ability to dissipate heat
when tested under controlled conditions on a specified indoor laboratory test wheel.
Sustained high temperature can cause the material of the tire to degenerate and reduce tire
life, and excessive temperature can lead to sudden tire failure. The grade C corresponds to a
level of performance which all passenger car tires must meet under the Federal Motor Safety
Standard No. 109. Grades B and A represent higher levels of performance on the laboratory
test wheel than the minimum required by law.
Warning: The temperature grade for this tire is established for a tire that is properly inflated
and not overloaded. Excessive speed, underinflation, or excessive loading, either separately
or in combination, can cause heat buildup and possible tire failure.