Uniform tire quality grading standards
This information indicates the rela- tive performance of passenger car tires in the area of treadwear, traction, and temperature resis- tance. This is to aid the consumer in making an informed choice in the purchase of tires.
Quality grades can be found where applicable on the tire sidewall be- tween tread shoulder and maximum section width.
For example:
TREADWEAR 200 TRACTION AA TEMPERATURE A
The quality grades apply to new pneumatic tires for use on passen- ger cars. However, they do not apply to deep tread, winter type snow tires, space-saver or tempor- ary use spare tires, tires with nominal rim diameters of 12 inches or less, or to some limited produc- tion tires.
Uniform tire quality grading standards 527
The treadwear grade is a compara- tive rating based on the wear rate of the tire when tested under con- trolled 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 govern- ment 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.
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 spe- cified government test surfaces of asphalt and concrete.
A tire marked C may have poor traction performance.
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 con- ditions on a specified indoor labora- tory 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 Stan- dards No. 109.
Grades B and A represent higher levels of performance on the la- boratory test wheel than the mini- mum required by law.
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