DOT Tire Quality Grading (U.S. Vehicles)

The tires on your vehicle meet all U.S. Federal Safety Requirements. All tires are also graded for treadwear, traction, and temperature performance according to Department of Transportation (DOT) standards. The following explains these gradings.

Uniform Tire Quality Grading

Quality grades can be found where applicable on the tire sidewall between tread houlder and maximum section width.

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. For example, a tire graded 150 would wear one and one-half (1 1/2) times as well on the government 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.

 

Uniform Tire Quality Grading

For example:

Treadwear 200

Traction AA

Temperature A

All passenger car tires must conform to Federal

Safety Requirements in addition to these grades.

Traction

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 asphat and concrete. A tire marked C may have poor traction performance.

Traction

Warning: The traction grade assigned to this tire is abased on straight-ahead braking traction tests, and does not include acceleration, cornering, hydroplaning, or peak traction characteristics.

Temperature

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 heate 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 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.

Temperature

Warning: The temperature grade for this tire is established for a tire that is properly inflated an not overloaded. Excessive speed, underinflation or excessive loading, either separately or in combination, can cause heat buildup and poss tire failure.

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