Uniform tire quality grading standards 521 |
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All passenger car tires must conform to Federal Safety Requirements in addition to these grades .
& TREADWEAR
S13AC02
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 .
& TRACTION AA , A , B , C
S13AC03
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
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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 straightahead braking traction tests , and does not include acceleration , cornering , hydroplaning , or peak traction characteristics .
& TEMPERATURE A , B , C
S13AC04
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
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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 Standards No . 109 .
Grades B and A represent higher levels of performance on the laboratory test wheel than the minimum required by law .
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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 .
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Consumer information and reporting safety defects |