Tire Tread; Summer Tires - Mini COOPER S Owner's Manual

DOT Quality Grades
Treadwear
Traction AA A B C
Temperature A B C
All passenger vehicle tires must conform to
Federal Safety Requirements in addition to
these grades.
Treadwear
The treadwear grade is a comparative rating
based on the wear rate of the tire when tested
under controlled conditions on a specified gov‐
ernment test course. E.g., a tire graded 150
would wear one and one-half, 1 g, 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
variations in driving habits, service practices
and differences in road characteristics and cli‐
mate.
Traction
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 control‐
led conditions on specified government test
surfaces of asphalt and concrete. A tire marked
C may have poor traction performance.
The traction grade assigned to this tire is based
on straight-ahead braking traction tests, and
does not include acceleration, cornering, hy‐
droplaning, or peak traction characteristics.
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 ma‐
terial of the tire to degenerate and reduce tire
life, and excessive temperature can lead to
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Wheels and tires
sudden tire failure. The grade C corresponds to
a level of performance which all passenger ve‐
hicle tires must meet under the Federal Motor
Vehicle Safety Standard No. 109. Grades Band A
represent higher levels of performance on the
laboratory test wheel than the minimum re‐
quired by law.
WARNING
The temperature grade for this tire is es‐
tablished for a tire that is properly inflated and
not overloaded. Excessive speed, underinfla‐
tion, or excessive loading, either separately or
in combination, can cause heat buildup and
possible tire failure.◀
RSC – Run-flat tires
Run-flat tires, refer to page 200, are labeled
with a circular symbol containing the letters
RSC marked on the sidewall.
M+S
Winter and all-season tires with better cold
weather performance than summer tires.

Tire tread

Summer tires

Do not drive with a tire tread depth of less than
0.12 in/3 mm.
There is an increased risk of hydroplaning if the
tire tread depth is less than 0.12 inches/3 mm.
Winter tires
Do not drive with a tire tread depth of less than
0.16 inches/4 mm.
Below a tread depth of 0.16 inches/4 mm, tires
are less suitable for winter operation.
MOBILITY
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