Tire coding, Whee ls and tire s – Mini 2008 Cooper User Manual

Page 104

Whee

ls and tire

102

Tire coding

Knowledge of the labeling on the side of the tire
makes it easier to identify and choose the right
tires.

Tire size

Speed code letter

Q = up to 100 mph or 160 km/h
T = up to 118 mph or 190 km/h
H = up to 131 mph or 210 km/h
V = up to 150 mph or 240 km/h
W = up to 167 mph or 270 km/h
Y = up to 186 mph or 300 km/h

Tire Identification Number

Tires with DOT codes meet the guidelines of the
US Department of Transportation.
DOT code:

Uniform Tire Quality Grading

Quality grades can be found where applicable
on the tire sidewall between tread shoulder and
maximum section width. For example:
Tread wear 200 Traction AA
Temperature A

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 gov-
ernment 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, how-
ever, 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 government test sur-
faces 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, corner-
ing, hydroplaning, or peak traction characteris-
tics.

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. Sus-
tained 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

e.g.
Nominal width in mm
Aspect ratio in

Radial belt construction
Rim diameter in inches
Load rating,
not on ZR tires
Speed code letter, in
front of the R on ZR tires

225/45 R 17 91 V

e.g.
Manufacturer's
code for tire make
Tire size and
tire design
Tire age

DOT xxxx xxx 4707