Tire Replacement - BMW X5 3.0i Owner's Manual

Tire replacement

146n
To m aintain good handling and vehicle
response, use only tires of a single
tread configuration from a single manu-
facturer. BM W tests and approves
w heel/ tire com binations. Refer to
page 148.
DOT Quality Grades
Treadw ear
Traction AA A B C
Tem perature A B C
All passenger car tires m ust
conform to Federal Safety
Requirem ents in addition to these
grades.<
Treadw ear
The treadw ear grade is a com parative
rating based on the w ear rate of the tire
w hen tested under controlled condi-
tions on a specified governm ent test
course.
For exam ple, a tire graded 150 w ould
w ear one and one- half (1 g) tim es as
w ell on the governm ent course as a tire
graded 100. The relative performance
of tires depends upon the actual condi-
tions of their use, how ever, and may
depart significantly from the norm due
to variations in driving habits, service
practices and differences in road char-
acteristics and climate.
Traction
The traction grades, from highest to
low est, are AA, A, B, and C.
Those grades represent the tire's ability
to stop on w et pavem ent as m easured
under controlled conditions on speci-
fied government test surfaces of
asphalt and concrete. A tire m arked C
may have poor traction perform ance.
The traction grade assigned to
this tire is based on straight-
ahead braking traction tests, and does
not include acceleration, cornering,
aquaplaning, or peak traction charac-
teristics.<
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
w hen tested under controlled condi-
tions on a specified indoor laboratory
test w heel.
Sustained high tem perature can cause
the material of the tire to degenerate
and reduce tire life, and excessive
tem perature can lead to a sudden flat
tire. The grade C corresponds to a level
of performance w hich all passenger car
tires must meet under the Federal
M otor Vehicle Safety Standard No. 109.
Grades B and A represent higher levels
of perform ance on the laboratory test
w heel than the m inim um required by
law .
The tem perature 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 com bination, can cause heat buildup
and possible a flat tire.<
U niform Tire Quality Grading
Quality grades can be found w here
applicable on the tire sidew all betw een
tread shoulder and m axim um section
w idth. For exam ple:
Treadw ear 200 Traction AA
Tem perature A
Do not use retreaded tires, since
driving safety m ay be im paired by
their use. This is due to the possible
variations in casing structures and, in
som e cases, to their extrem e age,
w hich can lead to a decrease in their
durability.<
Online Edition for Part No. 01 41 0 155 558 - © 09/00 BMW Group