FIAT 2013 500 - Manual (Page 206)

DEPARTMENT OF TRANSPORTATION UNIFORM
TIRE QUALITY GRADES
The following tire grading categories were established by
the National Highway Traffic Safety Administration. The
specific grade rating assigned by the tire’s manufacturer
in each category is shown on the sidewall of the tires on
your vehicle.
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 150 would wear one and one-half
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 charac-
teristics and climate.
Traction Grades
The Traction grades, from highest to lowest, are AA, A, B,
and C. These 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. A tire marked C may have poor traction perfor-
mance.
WARNING!
The traction grade assigned to this tire is based on
straight-ahead braking traction tests, and does not
include acceleration, cornering, hydroplaning, or
peak traction characteristics.
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Temperature Grades
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
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 Standard No. 109. Grades B and A repre-
sent 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 load-
ing, either separately or in combination, can cause
heat buildup and possible tire failure.
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