User Manual - Page 188

For 2017 ALFA ROMEO 4C SPIDER.

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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 varia-
tions in driving habits, service practices, and differences
in road characteristics 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 condi-
tions 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 perfor-
mance, which all passenger vehicle tires must meet
under the Federal Motor Vehicle Safety Standard No.
109. Grades B and A represent higher levels of perfor-
mance on the laboratory test wheel, than the minimum
required by law.
186 STARTING AND OPERATING
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