2012 GMC SIERRA 1500 wheel size

Black plate (37,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Seats and Restraints 3-37
WARNING (Continued)
proper service procedures, and
make sure the person performing
work for you is qualified to do so.
Adding Equipment to the
Airbag-Equipped Vehicle
Q: Is there anything I might addto or change about the vehicle
that could keep the airbags
from working properly?
A: Yes. If you add things that
change your vehicle's frame,
bumper system, height, front end
or side sheet metal, they may
keep the airbag system from
working properly. Changing or
moving any parts of the front
seats, safety belts, the airbag
sensing and diagnostic module,
steering wheel, instrument
panel, roof-rail airbag modules,
ceiling headliner or pillar garnish
trim, overhead console, front sensors, side impact sensors,
or airbag wiring can affect the
operation of the airbag system.
In addition, the vehicle may have
a passenger sensing system
for the right front passenger's
position, which includes sensors
that are part of the passenger's
seat. The passenger sensing
system may not operate properly
if the original seat trim is
replaced with non-GM covers,
upholstery or trim, or with
GM covers, upholstery or
trim designed for a different
vehicle. Any object, such as an
aftermarket seat heater or a
comfort enhancing pad or
device, installed under or on top
of the seat fabric, could also
interfere with the operation of
the passenger sensing system.
This could either prevent proper
deployment of the passenger
airbag(s) or prevent the
passenger sensing system
from properly turning off the
passenger airbag(s). See
Passenger Sensing System on
page 3‑32.
If you have any questions
about this, you should contact
Customer Assistance before you
modify your vehicle. The phone
numbers and addresses for
Customer Assistance are in
Step Two of the Customer
Satisfaction Procedure in
this manual. See
Customer
Satisfaction Procedure (U.S.
and Canada) on page 13‑1 or
Customer Satisfaction
Procedure (Mexico) on
page 13‑3.
If the vehicle has rollover
roof-rail airbags, see Different
Size Tires and Wheels on
page 10‑70 for additional
important information.

Black plate (44,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
5-44 Instruments and Controls
SERVICE PARK ASSIST
This message displays if there is a
problem with the Ultrasonic Rear
Parking Assist (URPA) system. Do
not use this system to help you
park. SeeUltrasonic Parking Assist
on page 9‑61 for more information.
See your dealer for service.
Ride Control System
Messages
SERVICE STABILITRAK
If the vehicle has StabiliTrak and
this message displays, it means
there may be a problem with the
StabiliTrak system. If you see this
message, try to reset the system.
Stop; turn off the engine for at least
15 seconds; then start the engine
again. If this message still comes
on, it means there is a problem. You
should see your dealer for service.
The vehicle is safe to drive;
however, you do not have the
benefit of StabiliTrak, so reduce
your speed and drive accordingly.
SERVICE TRACTION
CONTROL
If the vehicle has StabiliTrak, this
message displays when there is a
problem with the Traction Control
System (TCS). When this message
displays, the system will not limit
wheel spin. Adjust your driving
accordingly. See your dealer for
service. See StabiliTrak
®System on
page 9‑55 for more information.
STABILITRAK INITIALIZING
If the vehicle has StabiliTrak, this
message may come on if the
StabiliTrak system has not fully
initialized because of road
conditions or the incorrect tire size.
When the StabiliTrak system is fully
initialized, the message will turn
off. SeeStabiliTrak
®System on
page 9‑55 for more information.
If this message continues to be
displayed for multiple ignition cycles
and on different road surfaces, see
your dealer for service.
TRACTION XX
STABILITRAK XX
This message displays when the
traction control and/or StabiliTrak
systems have been turned on or off.
Adjust your driving accordingly.
To limit wheel spin and realize
the full benefits of the stability
enhancement system, you should
normally leave StabiliTrak on.
However, you should turn
StabiliTrak off if the vehicle gets
stuck in sand, mud, ice, or snow
and you want to rock the vehicle
to attempt to free it, or if you are
driving in extreme off-road
conditions and require more wheel
spin. See If the Vehicle Is Stuck on
page 9‑15. To turn the StabiliTrak
system on or off, see StabiliTrak
®
System on page 9‑55.

Black plate (2,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-2 Vehicle Care
Wheels and Tires
Tires . . . . . . . . . . . . . . . . . . . . . . . . 10-50
Tire Sidewall Labeling . . . . . . 10-52
Tire Designations . . . . . . . . . . . 10-54
Tire Terminology andDefinitions . . . . . . . . . . . . . . . . 10-55
Tire Pressure . . . . . . . . . . . . . . . 10-58
Tire Pressure for High-Speed Operation . . . . . . . . . . . . . . . . . 10-60
Tire Pressure Monitor System . . . . . . . . . . . . . . . . . . . 10-60
Tire Pressure Monitor Operation . . . . . . . . . . . . . . . . . 10-62
Tire Inspection . . . . . . . . . . . . . . 10-65
Tire Rotation . . . . . . . . . . . . . . . 10-65
Dual Tire Rotation . . . . . . . . . . 10-67
When It Is Time for New Tires . . . . . . . . . . . . . . . . . . . . . . 10-68
Buying New Tires . . . . . . . . . . . 10-68
Different Size Tires and Wheels . . . . . . . . . . . . . . . . . . . 10-70 Uniform Tire Quality
Grading . . . . . . . . . . . . . . . . . . . 10-70
Wheel Alignment and Tire Balance . . . . . . . . . . . . . . . . . . . 10-72
Wheel Replacement . . . . . . . . 10-72
Tire Chains . . . . . . . . . . . . . . . . . 10-74
If a Tire Goes Flat . . . . . . . . . . 10-75
Tire Changing . . . . . . . . . . . . . . 10-76
Full-Size Spare Tire . . . . . . . . 10-87
Jump Starting
Jump Starting . . . . . . . . . . . . . . 10-88
Towing
Towing the Vehicle . . . . . . . . . 10-93
Recreational Vehicle
Towing . . . . . . . . . . . . . . . . . . . . 10-93
Appearance Care
Exterior Care . . . . . . . . . . . . . . . 10-98
Interior Care . . . . . . . . . . . . . . . 10-101
Floor Mats . . . . . . . . . . . . . . . . 10-104
General Information
For service and parts needs,
visit your dealer. You will receive
genuine GM parts and GM-trained
and supported service people.
Genuine GM parts have one of
these marks:

Black plate (51,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-51
WARNING (Continued)
.Underinflated tires pose the
same danger as overloaded
tires. The resulting crash
could cause serious injury.
Check all tires frequently to
maintain the recommended
pressure. Tire pressure
should be checked when the
tires are cold.
.Overinflated tires are more
likely to be cut, punctured,
or broken by a sudden
impact—such as when
hitting a pothole. Keep tires at
the recommended pressure.
.Worn or old tires can cause a
crash. If the tread is badly
worn, replace them.
.Replace any tires that have
been damaged by impacts
with potholes, curbs, etc.
(Continued)
WARNING (Continued)
.Improperly repaired tires can
cause a crash. Only the
dealer or an authorized tire
service center should repair,
replace, dismount, and mount
the tires.
.Do not spin the tires in
excess of 56 km/h (35 mph)
on slippery surfaces such
as snow, mud, ice, etc.
Excessive spinning may
cause the tires to explode.
SeeTire Pressure for
High-Speed Operation on
page 10‑60 for inflation pressure
adjustment for high speed
driving.
20‐Inch Tires
If the vehicle has 20‐inch
P275/55R20 size tires, they are
classified as touring tires and
are designed for on road use. The low‐profile, wide tread
design is not recommended for
“off‐road”
driving or commercial
uses such as snow plowing.
See Off-Road Driving on
page 9‑6 andAdding a Snow
Plow or Similar Equipment on
page 9‑106 for additional
information.
Notice: 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.

Black plate (54,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-54 Vehicle Care
(F) Tire Ply Material:The type
of cord and number of plies in
the sidewall and under the tread.
(G) Single Tire Maximum
Load
:Maximum load that can
be carried and the maximum
pressure needed to support that
load when used as a single. For
information on recommended
tire pressure see Tire Pressure
on page 10‑58 andVehicle Load
Limits on page 9‑16.
Tire Designations
Tire Size
The examples show a typical
passenger vehicle and light
truck tire size.
Passenger (P‐Metric) Tire
(A) 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.
(B) Tire Width
:The three‐digit
number indicates the tire section
width in millimeters from
sidewall to sidewall.
(C) Aspect Ratio
:A two‐digit
number that indicates the tire
height‐to‐width measurements.
For example, if the tire size
aspect ratio is 75, as shown in
item C of the tire illustration, it would mean that the tire's
sidewall is 75 percent as high
as it is wide.
(D) 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; and the
letter B means belted‐bias ply
construction.
(E) Rim Diameter
:Diameter of
the wheel in inches.
(F) 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.

Black plate (55,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-55
Light Truck (LT‐Metric) Tire
(A) Light Truck (LT‐Metric)
Tire
:The United States version
of a metric tire sizing system.
The letters LT as the first two
characters in the tire size mean
a light truck tire engineered to
standards set by the U.S. Tire
and Rim Association.
(B) Tire Width
:The three‐digit
number indicates the tire section
width in millimeters from
sidewall to sidewall.
(C) Aspect Ratio
:A two‐digit
number that indicates the tire
height‐to‐width measurements.
For example, if the tire size
aspect ratio is 75, as shown
in item C of the light truck (LT‐Metric) tire illustration, it
would mean that the tire's
sidewall is 75 percent as high
as it is wide.
(D) 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; and the
letter B means belted‐bias ply
construction.
(E) Rim Diameter
:Diameter of
the wheel in inches.
(F) Load Range
:Load Range.
(G) Service Description
:The
service description indicates the
load index and speed rating of a
tire. If two numbers are given as
in the example, 120/116, then
this represents the load index for
single versus dual wheel usage (single/dual). 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
steering, power brakes, power
windows, power seats, and air
conditioning.
Aspect Ratio
:The relationship
of a tire's height to its width.

Black plate (62,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-62 Vehicle Care
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
located 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 on page 9‑16.
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. If the vehicle has DIC
buttons, tire pressure levels can be
viewed. For additional information
and details about the DIC operation
and displays, see Driver Information
Center (DIC) on page 5‑30 andTire
Messages on page 5‑45.
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 shows the size of the original
equipment tires and the correct
inflation pressure for the tires when
they are cold. See
Vehicle Load
Limits on page 9‑16, for an example
of the Tire and Loading Information
label and its location. Also see Tire
Pressure on page 10‑58.
The TPMS can warn about a
low tire pressure condition but it
does not replace normal tire
maintenance. See Tire Inspection
on page 10‑65, Tire Rotation on
page 10‑65 andTires on
page 10‑50.
Notice: Tire sealant materials are
not all the same. A non-approved
tire sealant could damage the
TPMS sensors. TPMS sensor
damage caused by using an
incorrect tire sealant is not
covered by the vehicle
warranty. Always use only the
GM-approved tire sealant
available through your dealer or
included in the vehicle.

Black plate (65,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-65
9. Turn the ignition switch toLOCK/OFF.
10. Set all four tires to the recommended air pressure
level as indicated on the Tire
and Loading Information label.
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.
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). See
Maintenance Schedule on
page 11‑3.
Tires are rotated to achieve
a uniform wear for all tires.
The first rotation is the most
important.
Any time unusual wear is
noticed, rotate the tires as
soon as possible and check the
wheel alignment. Also check for
damaged tires or wheels. See
When It Is Time for New Tires
on page 10‑68 andWheel
Replacement on page 10‑72. If your vehicle has dual rear
wheels, also see
Dual Tire
Rotation on page 10‑67.
Use this rotation pattern when
rotating the tires if the vehicle
has single rear wheels.