2021 CADILLAC CT4 service

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
VEHICLE CARE 341
When driving on a deflated run-flat
tire, avoid potholes and other road
hazards that could damage the tire
and/or wheel beyond repair. When a
tire has been damaged, or if driven
any distance while deflated, check
with an authorized run-flat tire
service center to determine whether
the tire can be repaired or should be
replaced. To maintain the run-flat
feature, all replacement tires must be
run-flat tires.
To locate the nearest GM or run-flat
servicing facility, call Customer
Assistance.
Self-Sealing Tires
This vehicle may have self-sealing
tires. These tires have a material
inside that can seal punctures from
common road hazards, such as nails
and screws, in the tread area. The tire
may lose air pressure if the sidewall is
damaged or the tread puncture is too
large. If the Tire Pressure Monitor
System indicates the tire pressure is
low, inspect the tire for damage and
inflate it to the recommended
pressure. If the tire is unable to
maintain the recommended pressure,contact the nearest authorized GM
servicing facility immediately for
inspection and repair or replacement.
To locate the nearest GM servicing
facility, call GM Customer Assistance.
Caution
Do not drive on a deflated
self-sealing tire as this could
damage the tire. Make sure the tire
is inflated to the recommended
pressure or have it immediately
repaired or replaced.
When tire replacement is needed
replace with a self-sealing tire,
because the vehicle does not come
with a spare tire or tire changing
equipment.
Low-Profile Tires
If the vehicle has 225/45R17 91V,
235/40R18 91V, 235/40R18 XL
95Y, or 235/35R19 XL 91V size
tires, they are classified as
low-profile tires. Caution
Low-profile tires are more
susceptible to damage from road
hazards or curb impact than
standard profile 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. The warranty does not cover
this type of damage. Keep tires set
to the correct inflation pressure and
when possible, avoid contact with
curbs, potholes, and other road
hazards.
Summer Tires
High Performance Summer Tires
This vehicle may come with
235/40R18 XL 95Y high performance
summer tires. These tires have a
special tread and compound that are
optimized for maximum dry and wet
road performance. This special tread
and compound will have decreased
performance in cold climates, and on
ice and snow. It is recommended that
winter tires be installed on the vehicle

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
342 VEHICLE CARE
if frequent driving at temperatures
below approximately 5 °C (40 °F) or on
ice or snow covered roads is expected.
SeeWinter Tires 0340.
Caution
High performance summer tires
have rubber compounds that lose
flexibility and may develop surface
cracks in the tread area at
temperatures below −7 °C (20 °F).
Always store high performance
summer tires indoors and at
temperatures above −7 °C (20 °F)
when not in use. If the tires have
been subjected to −7 °C (20 °F) or
less, let them warm up in a heated
space to at least 5 °C (40 °F) for
24 hours or more before being
installed or driving a vehicle on
which they are installed. Do not
apply heat or blow heated air
directly on the tires. Always inspect
tires before use. See Tire Inspection
0 352.
Tire Sidewall Labeling
Useful information about a tire is
molded into its sidewall. The
example shows a typical passenger
tire sidewall.
Passenger (P-Metric) Tire Example
(1) Tire Size:The tire size 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. (2) TPC Spec (Tire Performance
Criteria Specification)
:Original
equipment tires designed to GM's
specific tire performance criteria
have a TPC specification code
molded onto the sidewall. GM's
TPC specifications meet or exceed
all federal safety guidelines.
(3) DOT (Department of
Transportation)
:The
Department of Transportation
(DOT) code indicates that the tire
is in compliance with the U.S.
Department of Transportation
Motor Vehicle Safety Standards.
DOT Tire Date of Manufacture
:
The last four digits of the TIN
indicate the tire manufactured
date. The first two digits represent
the week and the last two digits,
the year. For example, the third
week of the year 2020 would have
a 4-digit DOT date of 0320. Week
01 is the first full week (Sunday
through Saturday) of each year.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
VEHICLE CARE 343
(4) Tire Identification Number
(TIN)
:The letters and numbers
following the DOT code are the
Tire Identification Number (TIN).
The TIN shows the manufacturer
and plant code, tire size, and date
the tire was manufactured. The
TIN is molded onto both sides of
the tire, although only one side
may have the date of
manufacture.
(5) Tire Ply Material
:The type
of cord and number of plies in the
sidewall and under the tread.
(6) Uniform Tire Quality
Grading (UTQG)
:Tire
manufacturers are required to
grade tires based on three
performance factors: treadwear,
traction, and temperature
resistance. For more information
see Uniform Tire Quality Grading
0 356. (7) Maximum Cold Inf lation
Load Limit
:Maximum load that
can be carried and the maximum
pressure needed to support
that load.
Tire Designations
Tire Size
The example shows a typical
passenger vehicle tire size.
Passenger (P-Metric) Tire
(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

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
VEHICLE CARE 351
message should go off after
successfully completing the sensor
matching process. See "TPMS
Sensor Matching Process" later in
this section.
.One or more TPMS sensors are
missing or damaged. The
malfunction light and the DIC
message should go off when the
TPMS sensors are installed and the
sensor matching process is
performed successfully. See your
dealer for service.
.Replacement tires or wheels do not
match the original equipment tires
or wheels. Tires and wheels other
than those recommended could
prevent the TPMS from functioning
properly. SeeBuying New Tires
0 354.
.Operating electronic devices or
being near facilities using radio
wave frequencies similar to the
TPMS could cause the TPMS
sensors to malfunction.
If the TPMS is not functioning
properly it cannot detect or signal a
low tire pressure condition. See your dealer for service if the TPMS
malfunction light and DIC message
come on and stay on.
Tire Fill Alert (If Equipped)
This feature provides visual and
audible alerts outside the vehicle to
help when inflating an underinflated
tire to the recommended cold tire
pressure.
When the low tire pressure warning
light comes on:
1. Park the vehicle in a safe, level place.
2. Set the parking brake firmly.
3. Place the vehicle in P (Park).
4. Add air to the tire that is underinflated. The turn signal lamp
will flash.
When the recommended pressure
is reached, the horn sounds once
and the turn signal lamp will stop
flashing and briefly turn solid.
Repeat these steps for all
underinflated tires that have
illuminated the low tire pressure
warning light.
{Warning
Overinflating a tire could cause the
tire to rupture and you or others
could be injured. Do not exceed the
maximum pressure listed on the
tire sidewall. See Tire Sidewall
Labeling 0342 and
Vehicle Load Limits 0214.
If the tire is overinflated by more than
35 kPa (5 psi), the horn will sound
multiple times and the turn signal
lamp will continue to flash for several
seconds after filling stops. To release
and correct the pressure, while the
turn signal lamp is still flashing,
briefly press the center of the valve
stem. When the recommended
pressure is reached, the horn
sounds once.
If the turn signal lamp does not flash
within 15 seconds after starting to
inflate the tire, the tire fill alert has
not been activated or is not working.
If the hazard warning flashers are on,
the tire fill alert visual feedback will
not work properly.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
VEHICLE CARE 355
number will be followed by MS for
mud and snow. SeeTire Sidewall
Labeling 0342 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 0352.
{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)
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 0214.

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
VEHICLE CARE 357
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
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
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 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 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 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 nuts

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
VEHICLE CARE 359
Caution
If the vehicle is equipped with a
tire size other than 235/40R18 or
235/35R19, use tire chains only
where legal and only when
necessary. Use low profile chains
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 rear axle.
Don't use chains on the tires of the
front 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. If air goes out of
a tire, it is much more likely to leak
out slowly. SeeTires0339 for
additional information. But if there
ever is 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
dealer or an authorized tire service
center repair or replace the flat tire
as soon as possible.
If the vehicle has run-flat tires, there
is no need to stop on the side of the
road to change a flat tire. See Run-Flat
Tires 0340.
{Warning
Special tools and procedures are
required to service a run-flat tire.
If these special tools and
procedures are not used, injury or
vehicle damage may occur. Always
(Continued)

Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
2021 - CRC - 11/23/20
360 VEHICLE CARE
Warning (Continued)
be sure the proper tools and
procedures, as described in the
service manual, are used.
If a tire goes flat, avoid further tire
and wheel damage by driving slowly
to a level place, well off the road,
if possible. Turn on the hazard
warning flashers. See Hazard Warning
Flashers 0129.
The vehicle has no spare tire, no tire
changing equipment, and no place to
store a tire.
If the vehicle has self-sealing tires, see
Self-Sealing Tires 0341. Tread
punctures typically will not cause tires
to lose air. However, if the vehicle
does get a flat tire, there is no spare
tire, tire changing equipment, or place
to store a tire. Contact Roadside
Service for help.
This vehicle may come with a tire
sealant and compressor kit. To use the
tire sealant and compressor kit, see
Tire Sealant and Compressor Kit 0360.
Tire Sealant and
Compressor Kit
{Warning
Idling a vehicle in an enclosed area
with poor ventilation is dangerous.
Engine exhaust may enter the
vehicle. Engine exhaust contains
carbon monoxide (CO) which
cannot be seen or smelled. It can
cause unconsciousness and even
death. Never run the engine in an
enclosed area that has no fresh air
ventilation. For more information,
see Engine Exhaust 0226.
{Warning
Overinflating a tire could cause the
tire to rupture and you or others
could be injured. Be sure to read
and follow the tire sealant and
compressor kit instructions and
inflate the tire to its recommended
pressure. Do not exceed the
recommended pressure.
{Warning
Storing the tire sealant and
compressor kit or other equipment
in the passenger compartment of
the vehicle could cause injury. In a
sudden stop or collision, loose
equipment could strike someone.
Store the tire sealant and
compressor kit in its original
location.
If this vehicle has a tire sealant and
compressor kit, there may not be a
spare tire or tire changing equipment,
and on some vehicles there may not
be a place to store a tire.
The tire sealant and compressor can
be used to temporarily seal punctures
up to 6 mm (0.25 in) in the tread area
of the tire. It can also be used to
inflate an underinflated tire.
If the tire has been separated from the
wheel, has damaged sidewalls, or has
a large puncture, the tire is too
severely damaged for the tire sealant
and compressor kit to be effective. See
Roadside Service 0403.