AFS Wheels

Tire Quality Grading

Uniform tire quality grading - DOT quality grades
All Passenger Car Tires must conform to Federal Safety Requirements in addition to these grades.

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 a 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.

Traction AA, A, B, C
The traction grades, from highest to lowest, are AA (the highest), A, B, and C and they 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 braking (straight ahead) traction tests and does not include cornering (turning) traction.

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 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.

The temperature grade for a tire is established for a tire that is properly inflated and not overloaded. Excessive speed, under inflation, or excessive loading, either separately or in combination, can cause heat buildup and possible tire failure.

On actual tire labels, TREADWEAR grades will be indicated by numbers ("80") for example), and TRACTION and TEMPERATURE grades will be indicated by an encircled "AA", "A", "B", or "C". The Standard does not apply to deep tread, winter-type snow tires or to space-saver or temporary use spare tires nor to tires with nominal rim diameters of 10 to 12 inches. All-season tires, while identified as Mud and Snow tires (M+S), have been graded.
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