TIRE CODING
TIRE CONDITION
Standard No. 109. Grades B and A represent Inspect your tires frequently for tread wear,
Traction
higher levels of performance on the labora- signs of damage and for foreign objects
tory test wheel than the minimum required lodged in the tread. Check the tread depth.
by law.
The traction grades, from highest to low-
est, are AA, A, B, and C.
Those grades represent the tire's ability to
stop on wet pavement as measured under
controlled conditions on specified govern-
ment test surfaces of asphalt and concrete.
A tire marked C may have poor traction per-
formance.
Tire tread
The temperature grade for this tire is
established for a tire that is properly
inflated and not overloaded. Excessive
speed, underinflation, or excessive loading,
The tread depth should not fall below
ε in / 3 mm.
Below ε in / 3 mm tread depth, there is a
very high danger of hydroplaning at higher
either separately or in combination, can
speeds even if there is only a small amount
cause heat buildup and possible tire fail-
The traction grade assigned to this
tire is based on straight-ahead brak-
ing traction tests, and does not include
acceleration, cornering, hydroplaning, or
peak traction characteristics.<
of water on the road.
Below a tread depth of / in / 4 mm, win-
1
ure.<
6
ter tires display a perceptible decrease in
their ability to cope with winter driving
RSC: Run Flat tires
You will recognize Run Flat tires by a circu- conditions, and should be replaced in the
lar symbol containing the letters RSC on
the side of the tire, refer to page 101.
interest of safety.
Temperature
The temperature grades are A, the highest,
B and C, representing the tire's resistance
M+S
to the generation of heat and its ability to Winter and all-season tires.
dissipate heat when tested under con-
trolled conditions on a specified indoor lab- properties than summer tires.
oratory test wheel.
These have better winter performance
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
100
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