Owner's Manual

83
OVERVIEWREPAIRS OPERATION CONTROLSDATAINDEX
TIRE REPLACEMENT
To maintain good handling and vehicle
response, use only tires of a single tread
configuration from a single manufacturer.
The manufacturer of your MINI tests and
approves wheel and tire combinations.
Do not use retreaded tires, since
driving safety may be impaired. This
is due to the possible variations in casing
structures and, in some cases, to their
extreme age, which can lead to a decrease
in their durability.<
DOT Quality Grades
Tread wear
Traction AA A B C
Temperature A B C
All passenger car tires must conform
to Federal Safety Requirements in
addition to these grades.<
Tread wear
The tread wear 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 (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 climate.
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
controlled conditions on specified govern-
ment 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, hydroplaning, 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
material of the tire to degenerate and
reduce tire life, and excessive temperature
can lead to a sudden flat tire. The grade C
corresponds to a level of performance
which all passenger car tires must meet
under the Federal Motor Car Safety Stan-
dard No. 109. Grades B and A represent
higher levels of performance on the labora-
tory test wheel than the minimum required
by law.
The temperature grade for this tire is
established for a tire that is properly
inflated and not overloaded. Excessive
speed, underinflation, or excessive loading,
either separately or in combination, can
cause heat buildup and possible tire
failure.<
Uniform Tire Quality Grading
Quality grades can be found where appli-
cable on the tire sidewall between tread
shoulder and maximum section width. For
example:
Tread wear 200
Traction AA
Temperature A
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