Tires
Your new vehicle comes with high-quality tires made by
a leading tire manufacturer. If you ever have questions
about your tire warranty and where to obtain service,
see your GM Warranty booklet for details. For additional
information refer to the tire manufacturer’s booklet
included with your vehicle’s Owner’s Manual.
{CAUTION:
Poorly maintained and improperly used
tires are dangerous.
Overloading your tires can cause
overheating as a result of too much
friction. You could have an air-out and a
serious accident. SeeLoading Your
Vehicle on page 4-29.
CAUTION: (Continued)
CAUTION: (Continued)
Underin ated tires pose the same danger
as overloaded tires. The resulting accident
could cause serious injury. Check all tires
frequently to maintain the recommended
pressure. Tire pressure should be checked
when your tires are cold.
Overin ated tires are more likely to be
cut, punctured, or broken by a sudden
impact — such as when you hit a pothole.
Keep tires at the recommended pressure.
Worn, old tires can cause accidents. If
your tread is badly worn, or if your tires
have been damaged, replace them.
SeeInflation - Tire Pressure on page 5-57
for in ation pressure adjustment for high
speed driving.
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Winter Tires
If you expect to drive on snow or ice covered roads
often, you may want to get winter tires for your vehicle.
All season tires provide good overall performance on
most surfaces but they may not offer the traction
you would like or the same level of performance as
winter tires on snow or ice covered roads.
See your dealer for details regarding winter tire
availability and proper tire selection. Also, seeBuying
New Tires on page 5-60
If you choose to use winter tires:
•Use tires of the same brand and tread type on all
four wheel positions.
•Use only radial ply tires of the same size, load
range, and speed rating as the original
equipment tires.
Winter tires with the same speed rating as your original
equipment tires may not be available for H, V, W
and ZR speed rated tires. If you choose winter tires with
a lower speed rating, never exceed the tire’s maximum
speed capability.
Tire Sidewall Labeling
Useful information about a tire is molded into the
sidewall. The following illustration is an example of a
typical P-Metric tire sidewall.
(A) Tire Size:The tire size code is a combination of
letters and numbers used to define a particular
tire’s width, height, aspect ratio, construction type, and
service description. See the Tire Size illustration
later in this section for more detail.
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Tire Size
The following illustration shows, an example of, a typical
passenger car tire size.
(A) Passenger (P-Metric) Tire:The United States
version of a metric tire sizing system. The letter P as the
first character in the tire size means a passenger
vehicle tire engineered to standards set by the U.S. Tire
and Rim Association.
(B) Tire Width:The three-digit number indicates the
tire section width in millimeters from sidewall to sidewall.
(C) Aspect Ratio:A two-digit number that indicates
the tire height-to-width measurements. For example, if
the tire size aspect ratio is 75, as shown in item C, of the
illustration, it would mean that the tire’s sidewall is
75 percent as high as it is wide.(D) Construction Code:A letter code is used to indicate
the type of ply construction in the tire. The letter R means
radial ply construction; the letter D means diagonal or
bias ply construction; and the letter B means belted-bias
ply construction.
(E) Rim Diameter:Diameter of the wheel in inches.
(F) Service Description:The service description
indicates the load range and speed rating of a tire. The
load index can range from 1 to 279. Speed ratings
range from A to Z.
Tire Terminology and De nitions
Air Pressure:The amount of air inside the tire pressing
outward on each square inch of the tire. Air pressure
is expressed in pounds per square inch (psi) or
kilopascal (kPa).
Accessory Weight:This means the combined weight
of optional accessories. Some examples of optional
accessories are, automatic transmission, power steering,
power brakes, power windows, power seats, and air
conditioning.
Aspect Ratio:The relationship of a tire’s height to
its width.
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Treadwear
The treadwear 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
a half (1.5) 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 – AA, A, B, C
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 surfaces of
asphalt and concrete. A tire marked C may have poor
traction performance. Warning: 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 – A, B, C
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 indoorlaboratory test wheel. Sustained 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
meet under the Federal Motor Vehicle Safety Standard
No. 109. Grades B and A represent higher levels of
performance on the laboratory test wheel than the
minimum required by law.
Warning: 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.
Wheel Alignment and Tire Balance
The tires and wheels on your vehicle were aligned
and balanced carefully at the factory to give you the
longest tire life and best overall performance.
Adjustments to wheel alignment and tire balancing will
not be necessary on a regular basis. However, if
you notice unusual tire wear or your vehicle pulling to
one side or the other, the alignment may need to
be checked. If you notice your vehicle vibrating when
driving on a smooth road, your tires and wheels
may need to be rebalanced. See your dealer for
proper diagnosis.
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