Volvo 2001 S80 Operation And Care Manual page 62

Uniform tire quality grading
All passenger car tires must conform to Federal Safety Requirements in addition to these grades
Quality grades can be found, where applicable, on the tire sidewall between the tread should and maximum section
width. For example:
Treadwear 200 Traction AA Temperature A
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 many depart significantly from the norm due to variation in driving habits,
service practices and differences in road characteristics and climate.
TRACTION
The traction grades, from highest to lowest, are AA, A, B, and C, 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
The temperature grades are AA (the highest), A, 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 minimum level of performance that all
passenger car tires must meet under the Federal Motor 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, under-inflation, or excessive loading, either separately or in combination, can cause heat buildup and possible
tire failure.
pg. 88 Changing wheels