wheel CADILLAC STS 2006 1.G Repair Manual

Low-Prole Performance Tires
If your vehicle has P255/45R18 99Y size tires on the
front wheels and P275/40R19 100Y size tires on the rear
wheels, they are classied as low-prole performance
tires. These tires are designed for very responsive
driving on wet or dry pavement. You may also notice
more road noise with low-prole performance tires and
that they tend to wear faster. These performance
tires are not rated as all-season tires. Winter tires
are recommended for snow or ice covered roads.
Notice:If your vehicle has low-prole tires, they
are more susceptible to damage from road hazards
or curb impact than standard prole tires. Tire
and/or wheel assembly damage can occur when
coming into contact with road hazards like,
potholes, or sharp edged objects, or when sliding
into a curb. Your GM warranty does not cover
this type of damage. Keep tires set to the correct
ination pressure and, when possible avoid contact
with curbs, potholes, and other road hazards.
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 5-72.
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, Y
and ZR speed rated tires. If you choose winter tires with
a lower speed rating, never exceed the tire’s maximum
speed capability.
5-57

Tire Size
The following illustration shows an example of a typical
passenger vehicle tire size.
(A) Passenger (P-Metric) Tire:The United States
version of a metric tire sizing system. The letter P as the
rst 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 60, as shown in item C of the
illustration, it would mean that the tire’s sidewall is
60 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:These characters represent
the load range and speed rating of the tire. The load
index represents the load carry capacity a tire is certied
to carry. The load index can range from 1 to 279. The
speed rating is the maximum speed a tire is certied
to carry a load. Speed ratings range from A to Z.
Tire Terminology and Denitions
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.
5-60

Run-Flat Tires (STS-V)
If your vehicle has run-at tires, there is no spare tire
and no tire changing equipment. Your vehicle also has a
Tire Pressure Monitor System (TPMS) which will alert
you if there is a loss of tire pressure in any of the tires.
SeeTire Pressure Monitor System on page 5-66.
{CAUTION:
When the low tire warning light is displayed on
the instrument panel cluster, your vehicle’s
handling capabilities will be reduced during
severe maneuvers. If you drive too fast, you
could lose control of your vehicle. You or
others could be injured. Do not drive over
55 mph (90 km/h) when the low tire warning
light is displayed. Drive cautiously and check
your tire pressures as soon as you can.If a tire goes at, you will not need to stop on the side
of the road to change the tire. You can just keep on
driving. The vehicle’s run-at tires can operate effectively
with no air pressure for up to 50 miles (80 km) at
speeds up to 55 mph (90 km/h). The shorter the
distance you drive and the slower the speed, the greater
the chance that the tire will not have to be replaced.
When a tire is lled with air, it provides a cushion
between the road and the wheel. Because you will not
have this cushion when driving on a deated run-at
tire, try to avoid potholes that could damage your wheel
and require replacement of it.
Some road hazards can damage a tire beyond repair.
This damage could occur even before you have driven
on the tire in a deated condition. When a tire has been
damaged, or if you have driven any distance on a
deated run-at tire, check with an authorized run-at
tire service center, as soon as possible, to determine
whether the tire can be repaired or should be replaced.
5-63

To maintain your vehicle’s run-at feature, all
replacement tires must be self-supporting tires.
To locate the nearest GM or authorized run-at
servicing facility, call Roadside Service. See
Roadside Service on page 7-5for details.
{CAUTION:
Run-at tires are constructed differently than
other tires and could explode during improper
service. You or others could be injured or
killed if you attempt to repair, replace,
dismount, or mount a run-at tire. Let only
an authorized run-at service center repair,
replace, dismount, and mount run-at tires.
The valve stems on your vehicle’s run-at tires have
sensors that are part of the Tire Pressure Monitor
System (TPMS). These sensors contain batteries which
are designed to last for 10 years under normal driving
conditions. See your GM dealer, if the TPMS sensors or
a wheel ever need replacement.
Notice:Using liquid sealants can damage the tire
valves and tire pressure monitor sensors in your
vehicle’s run-at tires. This damage would not
be covered by warranty. Do not use liquid sealants
in your vehicle’s run-at tires.
Ination - Tire Pressure
Tires need the correct amount of air pressure to operate
effectively.
Notice:Do not let anyone tell you that
under-ination or over-ination is all right. It is not.
If your tires do not have enough air (under-ination),
you can get the following:
Too much exing
Too much heat
Tire overloading
Premature or irregular wear
Poor handling
Reduced fuel economy
If your tires have too much air (over-ination), you
can get the following:
Unusual wear
Poor handling
Rough ride
Needless damage from road hazards
5-64

High Speed Operation
{CAUTION:
Driving at high speeds, 100 mph (160 km/h)
or higher, puts an additional strain on
tires. Sustained high-speed driving causes
excessive heat build up and can cause sudden
tire failure. You could have a crash and you or
others could be killed. Some high-speed rated
tires require ination pressure adjustment for
high speed operation. When speed limits and
road conditions are such that a vehicle can be
driven at high speeds, make sure the tires are
rated for high speed operation, in excellent
condition, and set to the correct cold tire
ination pressure for the vehicle load.
If you will be driving at high speeds, speeds of 100 mph
(160 km/h) or higher, where it is legal, set the cold
ination pressure to the maximum ination pressure
shown on the tire sidewall, or 38 psi (265 kPa),
whichever is lower. See the example following.When you end this high-speed driving, return the tires
to the cold ination pressure shown on the Tire and
Loading Information label. SeeLoading Your Vehicle
on page 4-32.
Example:
You will nd the maximum load and ination pressure
molded on the tire’s sidewall, in small letters, near
the rim ange. It will read something like this: Maximum
load 690 kg (1521 lbs) 300 kPa (44 psi) Max. Press.
For this example, you would set the ination pressure for
high-speed driving at 38 psi (265 kPa).
Tire Pressure Monitor System
The Tire Pressure Monitor System (TPMS) uses radio
and sensor technology to check tire pressure levels.
If your vehicle has this feature, sensors are mounted
onto each tire and wheel assembly, except the compact
spare tire and wheel. Tire pressure readings are sent
to a receiver located in the vehicle once every
60 seconds while the vehicle is being driven, and once
every 60 minutes if the vehicle is stationary for more
than 15 minutes.
Using the Driver Information Center (DIC), tire pressure
levels may be viewed by the driver. For additional
information and details about the DIC operation and
displays seeDIC Controls and Displays on page 3-74
andDIC Warnings and Messages on page 3-79.
5-66

TPM Sensor Identication Codes
Each TPMS sensor has a unique identication code.
Any time you replace one or more of the TPMS sensors
or rotate your vehicle’s tires, the identication codes
will need to be matched to the new tire/wheel position.
The sensors are matched to the tire/wheel positions
in the following order: driver’s side front tire, passenger’s
side front tire, passenger’s side rear tire, and driver’s
side rear tire using a TPMS diagnostic tool. See
your GM dealer for service.
The TPMS sensors may also be matched to each
tire/wheel position by increasing or decreasing the tire’s
air pressure. If using this method to match TPMS
sensors, the complete procedure outlined below must
be performed within 15 minutes of the vehicle being
stationary.
You will have one minute to match the rst tire/wheel
position, and ve minutes overall, to match all four
tire/wheel positions. If it takes longer than one minute to
match the rst tire and wheel, or more than ve minutes
to match all four tire/wheel positions, the matching
process stops and you will need to start over.The TPM matching process is outlined below:
1. Set the parking brake.
2. Press the push-button ignition switch to ACC.
3. Using the Keyless Access transmitter, lock and
unlock the vehicle’s doors.
4. Press the lock and unlock buttons, at the same
time, on the Keyless Access transmitter. A single
horn chirp will sound, indicating that the TPMS
is ready, and the sensor matching process
can begin.
5. Start with the driver’s side front tire.
6. Remove the valve cap from the valve stem. Activate
the TPMS sensor by increasing or decreasing the
tire’s air pressure for ve seconds, or until a horn
chirp sounds. The horn chirp, which may take up to
30 seconds to sound, conrms that the sensor
identication code has been matched to this tire
position. To decrease the tire’s air-pressure use the
pointed end of the valve cap, a pencil-style air
pressure gauge, or a key.
7. Proceed to the passenger’s side front tire, and
repeat the procedure in Step 6.
5-68

Tire Inspection and Rotation
Tire rotation is not recommended if your vehicle has the
following performance tire combinations:
P235/50R17 size tires on the front wheels and
P255/45R17 size tires on the rear wheels.
P235/50R18 size tires on the front wheels and
P255/45R18 size tires on the rear wheels.
P255/45R18 size tires on the front wheels and
P275/40R19 size tires on the rear wheels.
Different tire sizes should not be rotated front to rear.
Each tire and wheel should only be used in the original
front or rear position it is in.
Tire rotation is recommended if your vehicle is equipped
with P235/50R17 size tires on all four wheel positions
or 255/45ZR18 size tires on all four wheel positions.
These tires should be rotated every 5,000 to 8,000 miles
(8 000 to 13 000 km)
Any time you notice unusual wear, rotate your tires as
soon as possible and check wheel alignment. Also
check for damaged tires or wheels. SeeWhen It Is Time
for New Tires on page 5-71andWheel Replacement
on page 5-76for more information.The purpose of regular rotation is to achieve more
uniform wear for all tires on the vehicle. The rst rotation
is the most important. SeeScheduled Maintenance
on page 6-4.
When rotating P235/50R17 size tires or 255/45ZR18
size tires, always use the correct rotation pattern
shown here.
If your vehicle has a compact spare tire, do not include
the compact spare tire in the tire rotation.
After the tires have been rotated, adjust the front and
rear ination pressures as shown on the Tire and
Loading Information label.
5-70

Vehicles that have the Tire Pressure Monitor System
(TPMS) will need to have the TPMS sensors reset after
a tire rotation, seeTire Pressure Monitor System on
page 5-66.
Make certain that all wheel nuts are properly tightened.
See “Wheel Nut Torque” underCapacities and
Specications on page 5-116.
{CAUTION:
Rust or dirt on a wheel, or on the parts to
which it is fastened, can make wheel nuts
become loose after a time. The wheel could
come off and cause an accident. When you
change a wheel, remove any rust or dirt from
places where the wheel attaches to the vehicle.
In an emergency, you can use a cloth or a
paper towel to do this; but be sure to use a
scraper or wire brush later, if needed, to get all
the rust or dirt off. SeeChanging a Flat Tire
(STS Only) on page 5-83.
When It Is Time for New Tires
One way to tell when it is
time for new tires is to
check the treadwear
indicators, which will
appear when your tires
have only 1/16 inch
(1.6 mm) or less of tread
remaining.
You need a new tire if any of the following statements
are true:
You can see the indicators at three or more places
around the tire.
You can see cord or fabric showing through the
tire’s rubber.
The tread or sidewall is cracked, cut, or snagged
deep enough to show cord or fabric.
The tire has a bump, bulge, or split.
The tire has a puncture, cut, or other damage that
cannot be repaired well because of the size or
location of the damage.
5-71

{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), brands, 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), brands, or
types may also cause damage to your vehicle.
Be sure to use the correct size, brand, and
type of tires on all wheels. It is all right to drive
with your vehicle’s compact spare temporarily,
it was developed for use on your vehicle. See
Compact Spare Tire (STS Only) on page 5-94.
{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.
If you must replace your vehicle’s tires with those that
do not have a TPC Spec number, make sure they
are the same size, load range, speed rating, and
construction type (radial and bias-belted tires) as your
vehicle’s original tires.
5-73

Vehicles that have a tire pressure monitoring system
may give an inaccurate low-pressure warning if non-TPC
Spec rated tires are installed on it. Non-TPC Spec
rated tires may give a low-pressure warning that
is higher or lower than the proper warning level you
would get with TPC Spec rated tires. SeeTire Pressure
Monitor System on page 5-66.
Your vehicle’s original equipment tires are listed on
the Tire and Loading Information Label. This label
is attached to the vehicle’s center pillar (B-pillar). See
Loading Your Vehicle on page 4-32, for more information
about the Tire and Loading Information Label and its
location on your vehicle.
Vehicles that have 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 5-76.Different Size Tires and Wheels
If you add wheels or tires that are a different size than
your original equipment wheels and tires, this may
affect the way your vehicle performs, including its
braking, ride and handling characteristics, stability,
and resistance to rollover. Additionally, if your vehicle
has electronic systems such as, anti-lock brakes,
traction control, and electronic stability control, the
performance of these systems can be affected.
{CAUTION:
If you add different sized wheels, your
vehicle may not provide an acceptable
level of performance and safety if tires not
recommended for those wheels are selected.
You may increase the chance that you will
crash and suffer serious injury. Only use GM
specic wheel and tire systems developed for
your vehicle, and have them properly installed
by a GM certied technician.
SeeBuying New Tires on page 5-72andAccessories
and Modications on page 5-3for additional information.
5-74