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Except for snow tires, the DOT requires the manufacturers
to grade passenger car tires based on three performance factors:
tread wear, traction, and temperature resistance.
* More Than 100: Better
* 100: Baseline
* Less Than 100: Poorer
The tread wear grade is a comparative rating
based on the wear rate of the tire when tested under controlled
conditions on a specified government test track. A tire graded 200
would wear twice as long on the government test track as one graded
100. Your actual tire mileage depends upon the conditions of their
use and may vary due to driving habits, service practices, differences
in road characteristics and climate Note: Tread wear grades are
valid only for comparisons within a manufacturer's product line
.They are not valid for comparisons between manufacturers.
* A: Best
* B: Intermediate
* C: Acceptable
Traction grades represent the tire's ability
to stop on wet pavement as measured under controlled conditions
on specified government test surfaces of asphalt and concrete. The
Traction grade is based upon "straight ahead" braking
tests; it does not indicate cornering ability.
* A: Best
* B: Intermediate
* C: Acceptable
The temperature grades represent the tire's resistance
to the generation of heat when tested under controlled conditions
on a specified indoor laboratory test wheel. Sustained high temperatures
can cause the materials of the tire to degenerate and thus reduce
tire life. Excessive temperatures can lead to tire failure. Federal
law requires that all tires meet at least the minimal requirements
of Grade C.
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