tire size CADILLAC XT4 2021 User Guide

Cadillac XT4 Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
14584367) - 2021 - CRC - 10/14/20
VEHICLE CARE 313
(1) 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.
(2) Tire Width
:The 3-digit
number indicates the tire section
width in millimeters from sidewall
to sidewall.
(3) Aspect Ratio
:A 2-digit
number that indicates the tire
height-to-width measurements.
For example, if the tire size aspect
ratio is 75, as shown in item (3) of
the illustration, it would mean
that the tire's sidewall is
75 percent as high as it is wide.
(4) 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. (5) Rim Diameter
:Diameter of
the wheel in inches.
(6) Service Description
:These
characters represent the load
index and speed rating of the tire.
The load index represents the load
carrying capacity a tire is certified
to carry. The speed rating is the
maximum speed a tire is certified
to carry a load.
Tire Terminology and
Definitions
Air Pressure:The amount of air
inside the tire pressing outward
on each square inch of the tire.
Air pressure is expressed in kPa
(kilopascal) or psi (pounds per
square inch).
Accessory Weight
:The combined
weight of optional accessories.
Some examples of optional
accessories are automatic
transmission, power windows,
power seats, and air conditioning. Aspect Ratio
:The relationship of
a tire's height to its width.
Belt
:A rubber coated layer of
cords between the plies and the
tread. Cords may be made from
steel or other reinforcing
materials.
Bead
:The tire bead contains steel
wires wrapped by steel cords that
hold the tire onto the rim.
Bias Ply Tire
:A pneumatic tire in
which the plies are laid at
alternate angles less than
90 degrees to the centerline of the
tread.
Cold Tire Pressure
:The amount
of air pressure in a tire, measured
in kPa (kilopascal) or psi (pounds
per square inch) before a tire has
built up heat from driving. See
Tire Pressure 0316.
Curb Weight
:The weight of a
motor vehicle with standard and
optional equipment including the

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Passenger (P-Metric) Tire:A tire
used on passenger cars and some
light duty trucks and
multipurpose vehicles.
Recommended Inf lation
Pressure
:Vehicle manufacturer's
recommended tire inflation
pressure as shown on the tire
placard. See Tire Pressure 0316
and
Vehicle Load Limits 0215.
Radial Ply Tire
:A pneumatic tire
in which the ply cords that extend
to the beads are laid at 90 degrees
to the centerline of the tread.
Rim
:A metal support for a tire
and upon which the tire beads are
seated.
Sidewall
:The portion of a tire
between the tread and the bead.
Speed Rating
:An alphanumeric
code assigned to a tire indicating
the maximum speed at which a
tire can operate. Traction
:The friction between
the tire and the road surface. The
amount of grip provided.
Tread
:The portion of a tire that
comes into contact with the road.
Treadwear Indicators
:Narrow
bands, sometimes called wear
bars, that show across the tread of
a tire when only 1.6 mm (1/16 in)
of tread remains. See When It Is
Time for New Tires 0324.
UTQGS (Uniform Tire Quality
Grading Standards)
:A tire
information system that provides
consumers with ratings for a tire's
traction, temperature, and
treadwear. Ratings are determined
by tire manufacturers using
government testing procedures.
The ratings are molded into the
sidewall of the tire. See Uniform
Tire Quality Grading 0326. Vehicle Capacity Weight
:The
number of designated seating
positions multiplied by
68 kg (150 lb) plus the rated cargo
load. See Vehicle Load Limits 0215.
Vehicle Maximum Load on the
Tire
:Load on an individual tire
due to curb weight, accessory
weight, occupant weight, and
cargo weight.
Vehicle Placard
:A label
permanently attached to a vehicle
showing the vehicle capacity
weight and the original equipment
tire size and recommended
inflation pressure. See “Tire and
Loading Information Label” under
Vehicle Load Limits 0215.

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Remove the valve cap from the
tire valve stem. Press the tire
gauge firmly onto the valve to get
a pressure measurement. If the
cold tire inflation pressure
matches the recommended
pressure on the Tire and Loading
Information label, no further
adjustment is necessary. If the
inflation pressure is low, add air
until the recommended pressure is
reached. If the inflation pressure
is high, press on the metal stem in
the center of the tire valve to
release air.
Recheck the tire pressure with the
tire gauge.
Put the valve caps back on the
valve stems to keep out dirt and
moisture. Use only valve caps
designed for the vehicle by GM.
TPMS sensors could be damaged
and would not be covered by the
vehicle warranty.Tire Pressure for
High-Speed Operation
{Warning
Driving at high speeds, 160 km/h
(100 mph) or higher, puts additional
strain on tires. Sustained
high-speed driving causes excessive
heat buildup and can cause sudden
tire failure. This could cause a
crash, and you or others could be
killed. Some high-speed rated tires
require inflation pressure
adjustment for high-speed
operation. When speed limits and
road conditions allow the vehicle to
be driven at high speeds, make sure
the tires are rated for high-speed
operation, are in excellent
condition, and are set to the correct
cold tire inflation pressure for the
vehicle load.Vehicles with tire sizes listed in the
High Speed Operation Inflation
Pressures table require inflation
pressure adjustment when driving the
vehicle at speeds of 160 km/h
(100 mph) or higher. Set the cold tire
inflation pressure to the
corresponding value in the table for
the tire size on the vehicle.

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High Speed Operation Inf lation Pressures
Tire Size Cold Inf lation Pressure kPa (psi)
235/55R18 260 kPa (38 psi)
245/45R20 260 kPa (38 psi)
Return the tires to the recommended
cold tire inflation pressure when
high-speed driving has ended. See
Vehicle Load Limits 0215 and
Tire Pressure 0316.
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 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 inflated to the
inflation pressure recommended by
the vehicle manufacturer on the
vehicle placard or tire inflation pressure label. (If your vehicle has
tires of a different size than the size
indicated on the vehicle placard or tire
inflation pressure label, you should
determine the proper tire inflation
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 significantly under-inflated.
Accordingly, when the low tire
pressure telltale illuminates, you
should stop and check your tires as
soon as possible, and inflate them to
the proper pressure. Driving on a
significantly under-inflated tire causes
the tire to overheat and can lead to
tire failure. Under-inflation 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-inflation 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 flash for
approximately one minute and then
remain continuously illuminated. This

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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
0 319.
See Radio Frequency Statement 0383.
Tire Pressure Monitor
Operation
This vehicle may have a Tire Pressure
Monitor System (TPMS). The TPMS is
designed to warn the driver when a low tire pressure condition exists.
TPMS sensors are mounted onto each
tire and wheel assembly, excluding the
spare tire and wheel assembly. The
TPMS sensors monitor the air
pressure in the tires and transmit the
tire pressure readings to a receiver
located in the vehicle.
When a low tire pressure condition is
detected, the TPMS illuminates the
low tire pressure warning light on the
instrument cluster. If the warning
light comes on, stop as soon as
possible and inflate the tires to the
recommended pressure shown on the
Tire and Loading Information label.
See
Vehicle Load Limits 0215.
A message to check the pressure in a
specific tire displays in the Driver
Information Center (DIC). The low tire
pressure warning light and the DIC
warning message come on at each
ignition cycle until the tires are inflated to the correct inflation
pressure. Using the DIC, tire pressure
levels can be viewed. For additional
information and details about the DIC
operation and displays see
Driver
Information Center (DIC) 0114.
The low tire pressure warning light
may come on in cool weather when
the vehicle is first started, and then
turn off as the vehicle is driven. This
could be an early indicator that the air
pressure is getting low and needs to
be inflated to the proper pressure.
A Tire and Loading Information label,
attached to your vehicle, shows the
size of the original equipment tires
and the correct inflation pressure for
the tires when they are cold. See
Vehicle Load Limits 0215, for an
example of the Tire and Loading
Information label and its location.
Also see Tire Pressure 0316.
The TPMS can warn about a low tire
pressure condition but it does not
replace normal tire maintenance. See
Tire Inspection 0322, Tire Rotation
0 323 and
Tires 0308.

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.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.
Tire Rotation
Tires should be rotated every
12 000 km (7,500 mi). See
Maintenance Schedule0358.
Tires are rotated to achieve a
more uniform wear for all tires.
The first rotation is the most
important.
Anytime unusual wear is noticed,
rotate the tires as soon as
possible, check for proper tire
inflation pressure, and check for
damaged tires or wheels. If the
unusual wear continues after the
rotation, check the wheel
alignment. See When It Is Time for
New Tires 0324 and
Wheel Replacement 0328.
Use this rotation pattern when
rotating the tires.
Do not include the compact spare
tire in the tire rotation.
Adjust the front and rear tires to
the recommended inflation
pressure on the Tire and Loading
Information label after the tires
have been rotated. See Tire
Pressure 0316 and
Vehicle Load Limits 0215.
Reset the Tire Pressure Monitor
System. See Tire Pressure Monitor
Operation 0319. Check that all wheel nuts are
properly tightened. See
“Wheel
Nut Torque ”under Capacities and
Specifications 0371, and
“Removing the Flat Tire and
Installing the Spare Tire ”under
Tire Changing 0337.
{Warning
Rust or dirt on a wheel, or on
the parts to which it is fastened,
can cause wheel nuts to become
loose over time. The wheel
could come off and cause a
crash. When changing a wheel,
remove any rust or dirt from
places where the wheel attaches
to the vehicle. In an emergency,
a cloth or paper towel can be
used; however, use a scraper or
wire brush later to remove all
rust or dirt.

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month, remove the tires or raise the
vehicle to reduce the weight from the
tires.
Buying New Tires
GM has developed and matched
specific tires for the vehicle. The
original equipment tires installed
were designed to meet General
Motors Tire Performance Criteria
Specification (TPC Spec) system
rating. When replacement tires are
needed, GM strongly recommends
buying tires with the same TPC
Spec rating.
GM's exclusive TPC Spec system
considers over a dozen critical
specifications that impact the
overall performance of the 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 Specnumber will be followed by MS for
mud and snow. See
Tire Sidewall
Labeling 0310 for additional
information.
GM recommends replacing worn
tires in complete sets of four.
Uniform tread depth on all tires
will help to maintain the
performance of the vehicle.
Braking and handling performance
may be adversely affected if all the
tires are not replaced at the same
time. If proper rotation and
maintenance have been done, all
four tires should wear out at
about the same time. However,
if it is necessary to replace only
one axle set of worn tires, place
the new tires on the rear axle. See
Tire Rotation 0323.
{Warning
Tires could explode during
improper service. Attempting to
mount or dismount a tire could
cause injury or death. Only your
(Continued)
Warning (Continued)
dealer or authorized tire service
center should mount or
dismount the tires.
{Warning
Mixing tires of different sizes
(other than those originally
installed on the vehicle), brands,
tread patterns, or types may
cause loss of vehicle control,
resulting in a crash or other
vehicle damage. Use the correct
size, brand, and type of tire on
all wheels.
{Warning
Using bias-ply tires on the
vehicle may cause the wheel rim
flanges to develop cracks after
many miles of driving. A tire
and/or wheel could fail suddenly
(Continued)

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Warning (Continued)
and cause a crash. Use only
radial-ply tires with the wheels
on the vehicle.
Winter tires with the same speed
rating as the original equipment
tires may not be available for H, V,
W, Y and ZR speed rated tires.
Never exceed the winter tires’
maximum speed capability when
using winter tires with a lower
speed rating.
If the vehicle tires must be
replaced with a tire that does not
have a TPC Spec number, make
sure they are the same size, load
range, speed rating, and
construction (radial) as the
original tires.
The Tire and Loading Information
label indicates the original
equipment tires on the vehicle.
See Vehicle Load Limits 0215.Different Size Tires and
Wheels
If wheels or tires are installed that are
a different size than the original
equipment wheels and tires, vehicle
performance, including its braking,
ride and handling characteristics,
stability, and resistance to rollover
may be affected. If the vehicle has
electronic systems such as antilock
brakes, rollover airbags, traction
control, electronic stability control,
or All-Wheel Drive, the performance
of these systems can also be affected.
{Warning
If different sized wheels are used,
there may not be an acceptable
level of performance and safety if
tires not recommended for those
wheels are selected. This increases
the chance of a crash and serious
injury. Only use GM specific wheel
and tire systems developed for the
vehicle, and have them properly
installed by a GM certified
technician. See
Buying New Tires 0325 and
Accessories and Modifications 0283.
Uniform Tire Quality
Grading
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 tires, compact 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

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loading, either separately or in
combination, can cause heat
buildup and possible tire failure.
Wheel Alignment and Tire
Balance
The tires and wheels were aligned and
balanced at the factory to provide the
longest tire life and best overall
performance. Adjustments to wheel
alignment and tire balancing are not
necessary on a regular basis. Consider
an alignment check if there is unusual
tire wear or the vehicle is significantly
pulling to one side or the other. Some
slight pull to the left or right,
depending on the crown of the road
and/or other road surface variations
such as troughs or ruts, is normal.
If the vehicle is vibrating when driving
on a smooth road, the 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 nutsshould be replaced. If the wheel leaks
air, replace it. Some aluminum wheels
can be repaired. See your dealer if any
of these conditions exist.
Your dealer will know the kind of
wheel that is needed.
Each new wheel should have the same
load-carrying capacity, diameter,
width, offset, and be mounted the
same way as the one it replaces.
Replace wheels, wheel bolts, wheel
nuts, or Tire Pressure Monitor System
(TPMS) sensors with new GM original
equipment parts.
{Warning
Using the wrong replacement
wheels, wheel bolts, or wheel nuts
can be dangerous. It could affect
the braking and handling of the
vehicle. Tires can lose air, and
cause loss of control, causing a
crash. Always use the correct wheel,
wheel bolts, and wheel nuts for
replacement.
Caution
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.
Used Replacement Wheels
{Warning
Replacing a wheel with a used one
is dangerous. How it has been used
or how far it has been driven may
be unknown. It could fail suddenly
and cause a crash. When replacing
wheels, use a new GM original
equipment wheel.
Tire Chains
{Warning
If the vehicle has 235/60R18 or
245/45R20 size tires, do not use tire
chains. There is not enough
(Continued)

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Warning (Continued)
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 loss of
control and a crash. Use another
type of traction device only if its
manufacturer recommends it for
the vehicle's tire size combination
and road conditions. Follow that
manufacturer's instructions. To
avoid vehicle damage, drive slow
and readjust or remove the traction
device if it contacts the vehicle. Do
not spin the wheels. If traction
devices are used, install them on
the front tires.
Caution
If the vehicle is equipped with a tire
size other than 235/60R18 or
245/45R20, use tire chains only
where legal and only when
necessary. Use low profile chains(Continued)
Caution (Continued)
that add no more than 12 mm
thickness to the tire tread and inner
sidewall. Use chains that are the
proper size for the tires. Install
them on the tires of the front axle.
Do not use chains on the tires of
the rear axle. Tighten them as
tightly as possible with the ends
securely fastened. Drive slowly and
follow the chain manufacturer's
instructions. If the chains contact
the 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 the vehicle.
If a Tire Goes Flat
It is unusual for a tire to blow out
while driving, especially if the tires are
maintained properly. See Tires0308.
If air goes out of a tire, it is much
more likely to leak out slowly. But if
there is ever a blowout, here are a few
tips about what to expect and what
to do: If a front tire fails, the flat tire creates
a drag that pulls the vehicle toward
that side. Take your foot off the
accelerator pedal and grip the steering
wheel firmly. Steer to maintain lane
position, and then gently brake to a
stop, well off the road, if possible.
A rear blowout, particularly on a
curve, acts much like a skid and may
require the same correction as used in
a skid. Stop pressing the accelerator
pedal and steer to straighten the
vehicle. It may be very bumpy and
noisy. Gently brake to a stop, well off
the road, if possible.
{Warning
Driving on a flat tire will cause
permanent damage to the tire.
Re-inflating a tire after it has been
driven on while severely
underinflated or flat may cause a
blowout and a serious crash. Never
attempt to re-inflate a tire that has
been driven on while severely
underinflated or flat. Have your
(Continued)