warning GMC SIERRA 2021 Owner's Manual

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 373
The Trailering App can be used to view the
tire pressures after the recommended trailer
tire pressures have been entered. Refer to
the trailer tire placard on the trailer or the
trailer tire sidewall for the recommended
tire pressure.
The system is compatible with trailer tires
that have placard pressure values from
103 - 689 kpa (15 - 100 psi). The hole in the
wheel for the tire stem must be 11.43 mm
(0.453 in) in diameter. Use of the pressure
sensors on a wheel with a different stem
hole size could result in loss of air from
the tire.
If a low trailer tire pressure condition is
detected, the TTPMS displays a warning
message on the DIC. If the warning message
is displayed, stop as soon as possible and
inflate the tires to the recommended
pressure shown on the tire placard on the
trailer.
In addition, the TTPMS monitors the
temperature of the trailer tires. If the
system detects a high temperature on one
or more of the trailer tires, a warning
message will be displayed on the DIC. If this
warning message is displayed, stop as soon
as possible, and inspect the overheatedtrailer tire. Common causes for high trailer
tire temperature are underinflation,
overloading, or tire damage.
TTPMS Malfunction Message
The TTPMS will not function properly if one
or more of the trailer tire sensors are
missing or inoperable. If the system detects
a malfunction, a DIC message indicates that
the system requires service. Some of the
conditions that can cause the service
message to occur are:
.One of the trailer tires has been replaced
with the spare tire which does not have a
learned TTPMS sensor. The DIC message
should turn off after the pressure sensor
is installed in the tire, and the learning
process is performed successfully. See
"TTPMS Sensor Learning Process" under
Trailering App
0307.
.The TTPMS sensor learning process was
not done or not completed successfully.
The DIC message should go off after
successfully completing the sensor
learning process. See "TTPMS Sensor
Learning Process" under Trailering App
0 307.
.One or more TTPMS sensors are missing
or damaged. The DIC message should go
off when the TTPMS sensors are installed and the sensor learning process is
performed successfully. See "TTPMS
Sensor Learning Process" under
Trailering
App 0307.
.Operating electronic devices or being near
facilities using radio wave frequencies
similar to the TTPMS could cause
interference to the TTPMS which could
cause loss of signal reception from the
sensor.
.If the system does not receive the signal
from an individual sensor, an error
message may not occur until the vehicle
has been driver for a period of time.
If the TTPMS is not functioning properly, it
cannot detect or signal a low tire condition.
See your dealer for service if the DIC
message comes on and stays on when the
trailer tire pressures have been checked and
determined to be correct.
Tire Inspection
We recommend that the tires, including
the spare tire, if the vehicle has one, be
inspected for signs of wear or damage
at least once a month.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
374 Vehicle Care
Replace the tire if:
.The indicators at three or more
places around the tire can be seen.
.There is 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.
Tire Rotation
Tires should be rotated every 12 000 km
(7,500 mi). SeeMaintenance Schedule
0 409.
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 0375
and
Wheel Replacement 0378.Use this rotation pattern when rotating
the tires.
Do not include the 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 0367 and
Vehicle Load Limits 0222.
Reset the Tire Pressure Monitor System.
See Tire Pressure Monitor Operation
0 369.
Check that all wheel nuts are properly
tightened. See “Wheel Nut Torque”
under Capacities and Specifications
0 424.
{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.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 375
Lightly coat the inner diameter of the
wheel hub opening with wheel bearing
grease after a wheel change or tire
rotation to prevent corrosion or rust
build-up.
{Warning
Do not apply grease to the wheel
mounting surface, wheel conical
seats, or the wheel nuts or bolts.
Grease applied to these areas could
cause a wheel to become loose or
come off, resulting in a crash.
When It Is Time for New Tires
Factors, such as maintenance, temperatures,
driving speeds, vehicle loading, and road
conditions affect the wear rate of the tires.
Treadwear indicators are one way to tell
when it is time for new tires. Treadwear
indicators appear when the tires have only
1.6 mm (1/16 in) or less of tread remaining.
See Tire Inspection 0373 and
Tire Rotation 0374 for additional
information.
The rubber in tires ages over time. This also
applies to the spare tire, if the vehicle has
one, even if it is never used. Multiple factors
including temperatures, loading conditions,
and inflation pressure maintenance affect
how fast aging takes place. GM recommends
that tires, including the spare if equipped,
be replaced after six years, regardless of
tread wear. To identify the age of a tire, use
the tire manufacture date, which is the last four digits of the DOT Tire Identification
Number (TIN) molded into one side of the
tire sidewall. 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.
Vehicle Storage
Tires age when stored normally mounted on
a parked vehicle. Park a vehicle that will be
stored for at least a month in a cool, dry,
clean area away from direct sunlight to slow
aging. This area should be free of grease,
gasoline, or other substances that can
deteriorate rubber.
Parking for an extended period can cause
flat spots on the tires that may result in
vibrations while driving. When storing a
vehicle for at least a month, remove the
tires or raise the vehicle to reduce the
weight from the tires.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
376 Vehicle Care
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 Spec number will be followed
by MS for mud and snow. SeeTire
Sidewall Labeling 0362 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 Rotation0374.
{Warning
Tires could explode during improper
service. Attempting to mount or
dismount a tire could cause injury or
death. Only your 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 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.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 377
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. SeeVehicle Load Limits
0 222.
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 0376 and
Accessories and Modifications 0323.
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 also conform to federal
safety requirements and additional
General Motors Tire Performance
Criteria (TPC) standards.
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
All Passenger Car Tires Must Conform to
Federal Safety Requirements In Addition
To These Grades.
Treadwear
The treadwear grade is a comparative
rating based on the wear rate of the
tire when tested under controlled
conditions on a specified government
test course. For example, a tire graded
150 would wear one and one-half (1½)

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
378 Vehicle Care
times as well on the government course
as a tire 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 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.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 379
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 275/50R22, 275/60R20,
LT265/60R20, LT265/70R17, or LT275/65R18
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(Continued)
Warning (Continued)
instructions. To avoid vehicle damage,
drive slow and readjust or remove the
traction device if it is contacting the
vehicle. Do not spin the wheels.
If traction devices are used, install them
on the rear tires.
Caution
If the vehicle is equipped with a tire size
other than 275/50R22, 275/60R20,
LT265/60R20, LT265/70R17, or LT275/65R18
use tire chains only where legal and only
when necessary. Use chains that are the
proper size for the tires. Install them on
the tires of the rear axle. Do not 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.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
380 Vehicle Care
If a Tire Goes Flat
It is unusual for a tire to blowout 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. 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.
{Warning
Lifting a vehicle and getting under it to
do maintenance or repairs is dangerous
without the appropriate safety equipment
and training. If a jack is provided with
the vehicle, it is designed only for
changing a flat tire. If it is used for
anything else, you or others could be
badly injured or killed if the vehicle slips
off the jack. If a jack is provided with the
vehicle, only use it for changing a
flat tire.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 0142.
{Warning
Changing a tire can be dangerous. The
vehicle can slip off the jack and roll over
or fall causing injury or death. Find a
level place to change the tire. To help
prevent the vehicle from moving:
1. Set the parking brake firmly.
2. Shift the vehicle to P (Park).
3. For vehicles with four-wheel drive with an N (Neutral) transfer case
position, be sure the transfer case is
in a drive gear —not in N (Neutral).
4. Turn off the engine and do not restart while the vehicle is raised.
5. Do not allow passengers to remain in the vehicle.
6. Place wheel blocks, if equipped, on both sides of the tire at the opposite
corner of the tire being changed.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
384 Vehicle Care
If the wheel has a smooth center cap,
concealing access to the wheel nuts,
place the chisel end of the wheel wrench
in the slot on the wheel, and gently pry
it out.
If the wheel’s center cap does not
conceal the wheel nuts, the center cap
may remain during wheel removal. If the
removed wheel is to be stowed in the
hoist, the cap needs to be detached from
the wheel. Access the wheel from the
back side, and use a jack handle
extension to push out the center cap.
3. Use the wheel wrench and turn itcounterclockwise to loosen the wheel
nuts. Do not remove the wheel nuts yet.
{Warning
To avoid personal injury and vehicle
damage, disable the power assist steps
before using a jack or placing an object
under the vehicle. See Power Assist Steps
0 30.
Front Position
4. If the flat tire is on the front of the vehicle, position the jack under the
bracket attached to the vehicle's frame,
behind the flat tire, as shown.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 385
Rear Position
5. If the flat tire is on the rear, position the jack under the rear axle about 5 cm
(2 in) inboard of the shock absorber
bracket.
{Warning
Getting under a vehicle when it is lifted
on a jack is dangerous. If the vehicle slips
off the jack, you could be badly injured
or killed. Never get under a vehicle when
it is supported only by a jack.
{Warning
Raising the vehicle with the jack
improperly positioned can damage the
vehicle and even make the vehicle fall. To
help avoid personal injury and vehicle
damage, be sure to fit the jack lift head
into the proper location before raising
the vehicle.
{Warning
The jack has a feature to limit its travel
to prevent overextension. When the
height limit is reached, an increase in
resistance if felt when attempting to
raise the jack farther. Raising the jack
past the height limit can damage the jack
pin and cause the jack to lock into an
overextended position or not lower fully.
Do not attempt to force the jack higher
once the height limit is reached.
6. Turn the wheel wrench clockwise to raise the vehicle. Raise the vehicle far enough
off the ground so there is enough room
for the spare tire to fit under the
wheel well.7. Remove all the wheel nuts and take offthe flat tire.
{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.