2005 CADILLAC STS tires

Buying New Tires
To nd out what kind and size of tires you need, look at
the Tire and Loading Information label. SeeLoading
Your Vehicle on page 4-30, for an example of the label
and where it can be found on your vehicle.
The tires installed on your vehicle when it was new had a
Tire Performance Criteria Specication (TPC Spec)
number on each tire’s sidewall. When you get new tires,
GM recommends that you get tires with that same TPC
Spec number. That way your vehicle will continue to have
tires that are designed to give proper endurance,
handling, speed rating, load range, traction, ride, tire
pressure monitoring system performance and other
things during normal service on your vehicle. If your tires
have an all-season tread design, the TPC number will be
followed by an “MS” (for mud and snow).
The optional 18-inch performance tires, size 255/
45ZR18 99Y, used on some vehicles, meet the General
Motors Tire Performance Criteria Specication (TPC
Spec) rating but the TPC Spec code has not been molded
onto the tire’s sidewall. If your vehicle has these tires,
and you need to replace them, you can still get these
TPC spec rated tires by asking your GM dealer.Your GM dealer can order these tires by part number.
This way, your vehicle will continue to give the proper
endurance, handling, traction, and ride as the original
tires.
If you replace your tires with those not having a TPC
Spec number, make sure they are the same size,
load range, speed rating and construction type (bias,
bias-belted or radial) as your original 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 snow tires with
a lower speed rating, never exceed the tire’s maximum
speed capability.
If you replace your vehicle’s tires with those not having
a TPC Spec number, the tire pressure monitoring
system may give an inaccurate low-pressure warning.
Non-TPC Spec tires may give a low-pressure warning
that is higher or lower than the proper warning level you
would get with TPC Spec numbered tires.
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{CAUTION:
Mixing tires could cause you to lose control
while driving. If you mix tires of different sizes
(other than those originally installed on your
vehicle) or types (radial and bias-belted tires),
the vehicle may not handle properly, and you
could have a crash. Using tires of different
sizes (other than those originally installed on
your vehicle) may also cause damage to your
vehicle. Be sure to use the correct size and
type tires on all wheels. It is all right to drive
with your compact spare temporarily, it was
developed for use on your vehicle. See
Compact Spare Tire on page 5-84.
{CAUTION:
If you use bias-ply tires on your vehicle, the
wheel rim anges could develop cracks after
many miles of driving. A tire and/or wheel
could fail suddenly, causing a crash. Use only
radial-ply tires with the wheels on your vehicle.
Vehicles equipped with performance tires P235/
50R17 95V (front axle) and P255/45R17 98V (rear axle)
are mounted on wheels with different rim widths. The
front axle tires are mounted on rims 7.5 inches (19.05 cm)
wide and the rear axle tires require wheels with a
minimum rim width of 8 inches (20.32 cm). The original
equipment wheels designed for P255/45R17 98V size
tires are etched with the words REAR ONLY. When
replacing P255/45R17 98V size tires have them mounted
on wheels with a minimum width of 8 inches (20.32 cm)
and marked REAR ONLY. SeeWheel Replacement on
page 5-71.
5-69

Uniform Tire Quality Grading
Quality grades can be found where applicable on the
tire sidewall between tread shoulder and maximum
section width. For example:
Treadwear 200 Traction AA Temperature A
The following information relates to the system
developed by the United States National Highway
Traffic Safety Administration, which grades tires by
treadwear, traction and temperature performance.
(This applies only to vehicles sold in the United States.)
The grades are molded on the sidewalls of most
passenger car tires. The Uniform Tire Quality Grading
system does not apply to deep tread, winter-type
snow tires, space-saver or temporary use spare tires,
tires with nominal rim diameters of 10 to 12 inches
(25 to 30 cm), or to some limited-production tires.
While the tires available on General Motors passenger
cars and light trucks may vary with respect to these
grades, they must also conform to federal safety
requirements and additional General Motors Tire
Performance Criteria (TPC) standards.
Treadwear
The treadwear grade is a comparative rating based on
the wear rate of the tire when tested under controlled
conditions on a specied 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 signicantly 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 specied 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.
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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 specied 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
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 inated and not
overloaded. Excessive speed, underination, 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.
Wheel Replacement
Replace any wheel that is bent, cracked or badly rusted
or corroded. If wheel nuts keep coming loose, the
wheel, wheel bolts and wheel nuts should be replaced.
If the wheel leaks air, replace it (except some
aluminum wheels, which can sometimes be repaired).
See your dealer if any of these conditions exist.
Your dealer will know the kind of wheel you need.
Each new wheel should have the same load-carrying
capacity, diameter, width, offset and be mounted
the same way as the one it replaces.
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If you need to replace any of your wheels, wheel bolts
or wheel nuts, replace them only with new GM
original equipment parts. This way, you will be sure to
have the right wheel, wheel bolts and wheel nuts
for your vehicle.
{CAUTION:
Using the wrong replacement wheels, wheel
bolts or wheel nuts on your vehicle can be
dangerous. It could affect the braking and
handling of your vehicle, make your tires lose
air and make you lose control. You could have
a collision in which you or others could be
injured. Always use the correct wheel, wheel
bolts and wheel nuts for replacement.
Notice:The wrong wheel can also cause problems
with bearing life, brake cooling, speedometer or
odometer calibration, headlamp aim, bumper height,
vehicle ground clearance and tire or tire chain
clearance to the body and chassis.
SeeChanging a Flat Tire on page 5-74for more
information.
Used Replacement Wheels
{CAUTION:
Putting a used wheel on your vehicle is
dangerous. You can’t know how it’s been used
or how far it’s been driven. It could fail
suddenly and cause a crash. If you have to
replace a wheel, use a new GM original
equipment wheel.
5-72

Tire Chains
{CAUTION:
If your vehicle has P255/45R17 98V,
P255/45R18 99W or 255/45ZR18 99Y size tires,
do not use tire chains, there is not enough
clearance.
Tire chains used on a vehicle without the
proper amount of clearance can cause damage
to the brakes, suspension or other vehicle
parts. The area damaged by the tire chains
could cause you to lose control of your vehicle
and you or others may be injured in a crash.
CAUTION: (Continued)
CAUTION: (Continued)
Use another type of traction device only if its
manufacturer recommends it for use on your
vehicle and tire size combination and road
conditions. Follow that manufacturer’s
instructions. To help avoid damage to your
vehicle, drive slowly, readjust or remove the
device if it is contacting your vehicle, and do
not spin your wheels.
If you do nd traction devices that will t,
install them on the rear tires only.
Notice:If your vehicle has P235/50R17 95S size
tires, use tire chains only where legal and only when
you must. Use only SAE Class “S” type chains
that are the proper size for your tires. Install them
on the rear tires and tighten them as tightly as
possible with the ends securely fastened. Drive
slowly and follow the chain manufacturer’s
instructions. If you can hear the chains contacting
your vehicle, stop and retighten them. If the contact
continues, slow down until it stops. Driving too
fast or spinning the wheels with chains on will
damage your vehicle.
5-73

If a Tire Goes Flat
It is unusual for a tire to blowout while you’re driving,
especially if you maintain your tires properly. If air goes
out of a tire, it is much more likely to leak out slowly.
But if you should ever have a blowout, here are a
few tips about what to expect and what to do:
If a front tire fails, the at tire will create a drag that
pulls the vehicle toward that side. Take your foot off the
accelerator pedal and grip the steering wheel rmly.
Steer to maintain lane position, and then gently brake to
a stop well out of the traffic lane.
A rear blowout, particularly on a curve, acts much like a
skid and may require the same correction you would;
use in a skid. In any rear blowout, remove your foot from
the accelerator pedal. Get the vehicle under control
by steering the way you want the vehicle to go. It may
be very bumpy and noisy, but you can still steer. Gently
brake to a stop, well off the road if possible.{CAUTION:
Lifting a vehicle and getting under it to do
maintenance or repairs is dangerous without
the appropriate safety equipment and training.
The jack provided with your vehicle is
designed only for changing a at tire. If it is
used for anything else, you or others could be
badly injured or killed if the vehicle slips off
the jack. Use the jack provided with your
vehicle only for changing a at tire.
If a tire goes at, the next part shows how to use your
jacking equipment to change a at tire safely.
Changing a Flat Tire
If a tire goes at, avoid further tire and wheel damage
by driving slowly to a level place. Turn on your vehicle’s
hazard warning ashers. SeeHazard Warning Flashers
on page 3-6for more information.
5-74

Use the following diagram as a guide for storing the
compact spare tire in the trunk:
A. Compact Spare
Tire Cover
B. Plastic Wing Nut
C. Retainer
D. Jack Container
with Wheel Wrench
and JackE. Compact
Spare Tire
F. Foam Insert
G. Bolt
H. Wheel Wrench
I. Jack
J. Jack ContainerCompact Spare Tire
Although the compact spare tire was fully inated when
your vehicle was new, it can lose air after a time. Check
the ination pressure regularly. It should be
60 psi (420 kPa).
After installing the compact spare on your vehicle, you
should stop as soon as possible and make sure
your spare tire is correctly inated. The compact spare
is made to perform well at speeds up to 65 mph
(105 km/h) for distances up to 3,000 miles (5 000 km),
so you can nish your trip and have your full-size
tire repaired or replaced where you want. Of course, it
is best to replace your spare with a full-size tire as soon
as you can. Your spare will last longer and be in
good shape in case you need it again.
Notice:When the compact spare is installed, do
not take your vehicle through an automatic car wash
with guide rails. The compact spare can get
caught on the rails. That can damage the tire and
wheel, and maybe other parts of your vehicle.
Do not use your compact spare on other vehicles.
And do not mix your compact spare tire or wheel with
other wheels or tires. They will not t. Keep your
spare tire and its wheel together.
Notice:Tire chains will not t your compact spare.
Using them can damage your vehicle and can
damage the chains too. Do not use tire chains on
your compact spare.
5-84