Volvo S70 Owner's Manual page 143

1999 S70 & V70
Uniform tire quality grading
ALL PASSENGER CAR TIRES MUST CONFORM TO FEDERAL SAFETY REQUIREMENTS IN
ADDITION TO THESE GRADES
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 at 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 level of performance which 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, underinflation, or excessive loading, either separately or in combination,
can cause heat buildup and possible tire failure.
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