2008 CADILLAC CTS tire size

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 your vehicle has 235/50ZR18 size tires, they will
require ination pressure adjustment when driving your
vehicle at speeds of 100 mph (160 km/h) or higher.
Set the cold ination pressure to the maximum ination
pressure shown on the tire sidewall, or 44 psi (300 kPa),
whichever is lower. See the example following. When
you end this high-speed driving, return the tires to the
cold tire ination pressure shown on the Tire and Loading
Information label. SeeLoading the Vehicle on page 4-22
andInflation - Tire Pressure on page 5-66.
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 44 psi (300 kPa).
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Tire Pressure Monitor System
The Tire Pressure Monitor System (TPMS) uses radio
and sensor technology to check tire pressure levels.
The TPMS sensors monitor the air pressure in your
vehicle’s tires and transmit tire pressure readings to
a receiver located in the vehicle.
Each tire, including the spare (if provided), should be
checked monthly when cold and inated to the ination
pressure recommended by the vehicle manufacturer
on the vehicle placard or tire ination pressure label.
(If your vehicle has tires of a different size than the
size indicated on the vehicle placard or tire ination
pressure label, you should determine the proper
tire ination pressure for those tires.)
As an added safety feature, your vehicle has been
equipped with a tire pressure monitoring system (TPMS)
that illuminates a low tire pressure telltale when one
or more of your tires is signicantly under-inated.
Accordingly, when the low tire pressure telltale
illuminates, you should stop and check your tires
as soon as possible, and inate them to the proper
pressure. Driving on a signicantly under-inated
tire causes the tire to overheat and can lead to tire
failure. Under-ination also reduces fuel efficiency and
tire tread life, and may affect the vehicle’s handling
and stopping ability.Please note that the TPMS is not a substitute for proper
tire maintenance, and it is the driver’s responsibility to
maintain correct tire pressure, even if under-ination
has not reached the level to trigger illumination of
the TPMS low tire pressure telltale.
Your vehicle has also been equipped with a TPMS
malfunction indicator to indicate when the system is not
operating properly. The TPMS malfunction indicator is
combined with the low tire pressure telltale. When the
system detects a malfunction, the telltale will ash for
approximately one minute and then remain continuously
illuminated. This sequence will continue upon
subsequent vehicle start-ups as long as the malfunction
exists.
When the malfunction indicator is illuminated, the
system may not be able to detect or signal low tire
pressure as intended. TPMS malfunctions may occur
for a variety of reasons, including the installation of
replacement or alternate tires or wheels on the vehicle
that prevent the TPMS from functioning properly. Always
check the TPMS malfunction telltale after replacing one
or more tires or wheels on your vehicle to ensure that
the replacement or alternate tires and wheels allow the
TPMS to continue to function properly.
SeeTire Pressure Monitor Operation on page 5-70for
additional information.
5-69

A DIC warning message to check the pressure in a
specic tire is also shown on the DIC display screen.
The low tire pressure warning light and the DIC warning
message come at each ignition cycle until the tires
are inated to the correct ination pressure.
The low tire pressure warning light may come on in
cool weather when the vehicle is rst started, and then
turn off as you start to drive. This could be an early
indicator that the air pressure in the tire(s) are getting
low and need to be inated to the proper pressure.
The Tire and Loading Information label, attached to
your vehicle, shows the size of your vehicle’s original
equipment tires and the correct ination pressure for the
tires when they are cold. SeeLoading the Vehicle on
page 4-22, for an example of the Tire and Loading
Information label and its location on your vehicle.
Also seeInflation - Tire Pressure on page 5-66.Your vehicle’s TPMS can warn you about a low tire
pressure condition but it does not replace normal
tire maintenance. SeeTire Inspection and Rotation
on page 5-74andTires on page 5-58.
Notice:Using non-approved tire sealants could
damage the Tire Pressure Monitor System (TPMS)
sensors. TPMS sensor damage caused by using
an incorrect tire sealant is not covered by the
vehicle warranty. Always use the GM approved
tire sealant available through your dealer/retailer.
Your vehicle, when new, may have included a
factory-installed Tire Sealant and Compressor Kit.
This kit uses a GM approved liquid tire sealant. See
Tire Sealant and Compressor Kit (With Sealant Selector
Switch) on page 5-84orTire Sealant and Compressor
Kit (Without Sealant Selector Switch) on page 5-93.
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9. After hearing the conrming horn chirp, for the
driver side rear tire, the horn sounds two more
times to signal the tire learning mode is no longer
active. Turn the ignition switch to LOCK/OFF.
10. Set all four tires to the recommended air pressure
level as indicated on the tire and loading information
label.
11. Put the valve caps back on the valve stems.
Tire Inspection and Rotation
We recommend that you regularly inspect your
vehicle’s tires, including the spare tire, for signs
of wear or damage. SeeWhen It Is Time for New
Tires on page 5-75for more information.
Tires should be rotated every 5,000 to 8,000 miles
(8 000 to 13 000 km). SeeScheduled Maintenance
on page 6-4.
The purpose of a regular tire rotation is to achieve
a uniform wear for all tires on the vehicle. This will
ensure that your vehicle continues to perform most
like it did when the tires were new.
If your vehicle has 235/50ZR18 size tires, GM
recommends rotating these tires at 3,000 mile
(4 800 km) intervals. These tires are optimized fordry traction and handling performance. Tread life
may be 15,000 miles (24 140 km) or less for these
tires, depending on how and where you drive.
Any time you notice unusual wear, rotate your
vehicle’s 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 5-75andWheel Replacement on page 5-80
for more information.
When rotating your vehicle’s tires, always use the
correct rotation pattern shown here.
If your vehicle has a compact spare tire, do not
include it in the tire rotation.
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You need new tires 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.
The rubber in tires degrades over time, even if they are
not being used. This is also true for the spare tire, if your
vehicle has one. Multiple conditions affect how fast this
aging takes place, including temperatures, loading
conditions, and ination pressure maintenance. With
proper care and maintenance tires will typically wear out
before they degrade due to age. If you are unsure about
the need to replace your tires as they get older, consult
the tire manufacturer for more information.
Buying New Tires
GM has developed and matched specic tires for your
vehicle. The original equipment tires installed on
your vehicle, when it was new, were designed to meet
General Motors Tire Performance Criteria Specication
(TPC Spec) system rating. If you need replacement
tires, GM strongly recommends that you get tires with
the same TPC Spec rating. This way, your vehicle
will continue to have tires that are designed to give
the same performance and vehicle safety, during
normal use, as the original tires.
GM’s exclusive TPC Spec system considers over a
dozen critical specications that impact the overall
performance of your vehicle, including brake system
performance, ride and handling, traction control, and
tire pressure monitoring performance. GM’s TPC Spec
number is molded onto the tire’s sidewall near the tire
size. If the tires have an all-season tread design, the
TPC Spec number will be followed by an MS for mud
and snow. SeeTire Sidewall Labeling on page 5-60
for additional information.
GM recommends replacing tires in sets of four. This is
because uniform tread depth on all tires will help keep
your vehicle performing most like it did when the tires
were new. Replacing less than a full set of tires can affect
the braking and handling performance of your vehicle.
SeeTire Inspection and Rotation on page 5-74for
information on proper tire rotation.
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Winter tires with the same speed rating as your vehicle’s
original equipment tires may not be available for H, V,
W, Y, and ZR speed rated tires. If you choose snow tires
with a lower speed rating, never exceed the tire’s
maximum speed capability.
{CAUTION:
Mixing tires could cause you to lose
control while driving. If you mix tires of
different sizes, 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,
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 compact
spare temporarily, as it was developed for
use on your vehicle. SeeCompact Spare
Tire on page 5-111.
{CAUTION:
If you use bias-ply tires on the 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 the 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.
Vehicles that have a tire pressure monitoring system
could give an inaccurate low-pressure warning if
non-TPC Spec rated tires are installed on your vehicle.
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 5-69.
Your vehicle’s original equipment tires are listed on
the Tire and Loading Information Label. SeeLoading the
Vehicle on page 4-22, for more information about the
Tire and Loading Information Label and its location
on your vehicle.
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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, antilock 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 5-76andAccessories
and Modifications on page 5-4for additional information.
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 (NHTSA), 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 (UTQG)
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.
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Tire Chains
{CAUTION:
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. 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, re-adjust 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.
If a Tire Goes Flat
It is unusual for a tire to blowout while you are driving,
especially if you maintain your tires properly. SeeTires
on page 5-58. 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.
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