Maintenance
407
Tires and wheels
on the government course as a tire
graded 100.
The relative performance of tires
depends upon the actual conditions
of their use. Performance may
depart significantly from the norm
due to variations in driving habits,
service practices and differences in
road characteristics and climate.
These grades are molded on the
side-walls of passenger vehicle
tires. The tires available as standard
or optional equipment on your vehi
-
cle may vary with respect to grade.
Traction - AA, A, B & C
The traction grades, from highest to
lowest, are AA, A, B and C. Those
grades represent the tire's ability to
stop on wet pavement as measured
under controlled conditions on spec
-
ified government test surfaces of
asphalt and concrete. A tire marked
C may have poor traction perfor
-
mance.
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 char
-
acteristics.
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 condi
-
tions on a specified indoor labora
-
tory 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 cor
-
responds 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 labo
-
ratory test wheel than the mini
-
mum required by law.
Tire terminology and definitions
Refer to the following for detailed
definitions of the terms that are
found in the tire description.
Air Pressure The amount of air
inside the tire pressing outward on
the tire. Air pressure is expressed in
pounds per square inch (psi) or kilo
-
pascal (kPa).
Accessory Weight The combined
weight of optional accessories.
Some examples of optional accesso
-
ries are automatic transmission,
power seats, and air conditioning.
Aspect Ratio The relationship of a
tire's height to its width.
Belt A rubber coated layer of cords
that is located between the plies
and the tread. Cords may be made
from steel or other reinforcing
materials.
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