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324 VEHICLE CARE
Caution
Continuing to drive with worn-out
brake linings could result in costly
brake repairs.
Some driving conditions or climates
can cause a brake squeal when the
brakes are first applied, clearing up
following several applications. This
does not mean something is wrong
with the brakes.
Properly torqued wheel nuts are
necessary to help prevent brake
pulsation. When tires are rotated,
inspect brake linings for wear and
evenly tighten wheel nuts in the
proper sequence to torque
specifications. See Capacities and
Specifications 0396.
Brake pads should be replaced as
complete axle sets.
Brake Pedal Travel
See your dealer if the brake pedal does
not return to normal height, or if
there is a rapid increase in pedal
travel. This could be a sign that brake
service may be required.
Replacing Brake System Parts
Always replace brake system parts
with new, approved replacement parts.
If this is not done, the brakes may not
work properly. The braking
performance can change in many
ways if the wrong brake parts are
installed or if parts are improperly
installed.
Brake Pad Life System (If
Equipped)
When to Change Brake Pads
This vehicle has a system that
estimates the remaining life of the
front and rear brake pads. Brake pad
life is displayed in the Driver
Information Center (DIC), along with
a percentage for each axle. The system
must be reset every time the brake
pads are changed.
When the system has determined that
the brake pads need to be replaced, a
message will display, which may
include mileage remaining.
Brake pads should always be replaced
as complete axle sets.
How to Reset the Brake Pad Life
System
The system will automatically detect
when significantly worn brake pads
and sensors are replaced. When the
ignition is turned on after new pads
and sensors are installed, a message
will display. Follow the prompts to
reset the system.
The brake pad life system can also be
manually reset: 1. Display Brake Pad Life on the DIC. See Driver Information Center (DIC)
(Base Level) 0107 or
Driver Information Center (DIC)
(Uplevel) 0110.
2. Press the thumbwheel. Select front or rear pads as appropriate.
3. Select YES on the confirmation message. Repeat for pads on the
other axle if they were also
replaced.
Cadillac CT4 Owner Manual (GMNA-Localizing-U.S./Canada-14584335) -
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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.
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(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
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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 0346.
Curb Weight
:The weight of a
motor vehicle with standard and
optional equipment including the
maximum capacity of fuel, oil, and
coolant, but without passengers
and cargo.
DOT Markings
:A code molded
into the sidewall of a tire
signifying that the tire is in
compliance with the U.S.
Department of Transportation
(DOT) Motor Vehicle Safety Standards. The DOT code includes
the Tire Identification Number
(TIN), an alphanumeric designator
which can also identify the tire
manufacturer, production plant,
brand, and date of production.
GVWR
:Gross Vehicle Weight
Rating. See Vehicle Load Limits
0 214.
GAWR FRT
:Gross Axle Weight
Rating for the front axle. See
Vehicle Load Limits 0214.
GAWR RR
:Gross Axle Weight
Rating for the rear axle. See
Vehicle Load Limits 0214.
Intended Outboard Sidewall
:
The side of an asymmetrical tire
that must always face outward
when mounted on a vehicle.
Kilopascal (kPa)
:The metric unit
for air pressure.
Light Truck (LT-Metric) Tire
:A
tire used on light duty trucks and
some multipurpose passenger
vehicles.
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358 VEHICLE CARE
should 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 235/40R18 or
235/35R19 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 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 rear tires.