Tire Information
Tire Size Designation
A tire's sidewall is marked with a tire
size designation. You will need this
information when selecting replace-
ment tires for your vehicle. The
following explains what the letters and numbers in the tire size
designation mean.
(Example tire size designation)
P205/65R15 92S
P — Applicable vehicle type (tires
marked with the prefix "P" are
intended for use on passenger
vehicles; however, not all tires have this marking).
205 — Tire width in millimeters.
65 — Aspect ratio. The tire's section
height as a percentage of its width.
R — Tire construction code (Radial).
15 — Rim diameter in inches.
92 — Load Index, a numerical code
associated with the maximum load
the tire can carry.
S — Speed Symbol. See the speed
rating chart in this section for additional information.
Wheel Size Designation
Wheels are also marked with important information that you need
if you ever have to replace one. The
following explains what the letters and numbers in the wheel size
designation mean.
(Example wheel size designation)
15
x
6
JJ
15 — Rim diameter in inches.
6 — Rim width in inches.
JJ — Rim contour designation.
Tire Speed Ratings
The chart below shows many of the
different speed ratings currently
being used for passenger vehicle
tires. The speed symbol is part of the
tire size designation on the sidewall of the tire. This symbol corresponds
to that tire's designed maximum safe operating speed.
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Tire Information
Traction
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 as- signed to this tire is based on brak-
ing (straight ahead) traction tests
and does not include cornering (turning) traction. Temperature
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 over-
loaded. Excessive speed, underinfla-
tion, or excessive loading either
separately or in combination, can
cause heat build-up and possible tire
failure.
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