Ford 1996 Crown Victoria Manual page 280

Traction A B C
The traction grades, from highest to lowest, are
A, B, and C, and they 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 braking (straightahead) traction tests
and does not include cornering (turning)
traction.
Temperature A B C
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
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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