Mini 2003 Cooper User Manual

Page 90

TIRE REPLACEMENT

Tread wear

The tread wear grade is a comparative rat-
ing 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

γ – 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 per-
formance.

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.

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 con-
trolled conditions on a specified indoor lab-
oratory 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 Vehicle Safety
Standard 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 fai-
lure.

Uniform Tire Quality Grading

Quality grades can be found where applica-
ble on the tire sidewall between tread
shoulder and maximum section width.
For example:

Treadwear 200

Traction AA

Temperature A

Tire age

The date on which the tire was manufac-
tured is indicated by the code on the side-
wall:

DOT ... 1202 indicates that the tire was
manufactured in Week 12 of the year 2002.

The manufacturer of your MINI recom-
mends replacing all tires – including the
space-saver tire, regardless of actual wear –
after 6 years at the latest.

Run Flat tires

For replacement, use only Run Flat
tires, as in the event of a flat tire

there is no space-saver spare tire.
You will recognize Run Flat tires by a circu-
lar symbol containing the letters RSC on
the side of the tire, see pages

116

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