Fiat 124 SPIDER 2017 Owner's Manual page 287

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 performance.
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.
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 vehicle tires must
meet under the Federal Motor Vehicle
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.
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