Uniform Tire Quality Grading

The following information refers to the system developed by the U.S. National Highway Traffic Safety Administration (NHTSA), which grades tires for treadwear, traction, and temperature performance. This applies only to vehicles sold in the United States. The grades are molded into the sidewalls of most passenger vehicle tires. The Uniform Tire Quality Grading (UTQG) system does not apply to deep tread, winter or snow tires, compact spare tires, tires with rim diameters from 10 to 12 inches (25 to 30 cm), or to some limited-production tires.

While tires are available on General Motors passenger cars and light trucks may vary in relation to these ratings, they must also meet federal safety requirements and the additional General Motors Tire Performance Criteria (TPC) standards.

Quality grades can be found, where applicable, on the tire sidewall between the tread shoulder and the maximum section width. For example:

Treadwear 200 Traction AA Temperature A

All passenger car tires must meet federal safety requirements in addition to these ratings.

Sport Utility

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. For example, a tire graded 150 would wear one and one-half (1½) times as well as the government course 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.

Traction

Traction grades, from highest to lowest, are AA, A, B, and C. These grades represent the tire's ability to stop on wet pavement, 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.

Temperature

Temperature grades A (the highest), B, and C represent 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 tire material 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 Vehicle 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.