height GMC SIERRA 2011 User Guide

Black plate (31,1)GMC Sierra Owner Manual - 2011
Vehicle Care 10-31
Some driving conditions or climates
can cause a brake squeal when
the brakes are first applied or
lightly applied. 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 pads for wear and
evenly tighten wheel nuts in
the proper sequence to torque
specifications inCapacities and
Specifications on page 12‑2.
If the vehicle has rear drum brakes,
they do not have wear indicators,
but if a rear brake rubbing noise is
heard, have the rear brake linings
inspected immediately. Rear brake
drums should be removed and
inspected each time the tires are
removed for rotation or changing. Drum brakes have an inspection
hole to inspect lining wear during
scheduled maintenance. When
the front brake pads are replaced,
have the rear brakes inspected, too.
Brake linings should always 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 might
be required.
Brake Adjustment
Every time the brakes are applied,
with or without the vehicle moving,
the brakes adjust for wear.
Replacing Brake System Parts
The braking system on a vehicle is
complex. Its many parts have to be
of top quality and work well together
if the vehicle is to have really good
braking. The vehicle was designed
and tested with top-quality brake
parts. When parts of the braking
system are replaced, be sure to get
new, approved replacement parts.
If this is not done, the brakes might
not work properly. For example,
installing disc brake pads that
are wrong for the vehicle, can
change the balance between the
front and rear brakes
—for the
worse. The braking performance
expected can change in many
other ways if the wrong replacement
brake parts are installed.

Black plate (43,1)GMC Sierra Owner Manual - 2011
Vehicle Care 10-43
4. At a wall, measure from theground upward (A) to the
recorded distance from
Step 3 and mark it.
5. Draw or tape a horizontal line (B) on the wall the width of the
vehicle at the height of the
mark in Step 4. Notice:
Do not cover a headlamp
to improve beam cut-off when
aiming. Covering a headlamp may
cause excessive heat build-up
which may cause damage to the
headlamp.
6. Turn on the low-beam
headlamps and place a
piece of cardboard or equivalent
in front of the headlamp not
being adjusted. This allows
only the beam of light from the
headlamp being adjusted to be
seen on the flat surface.
7. Locate the vertical headlampaiming screws, which are under
the hood near each headlamp
assembly.
The adjustment screw can be
turned with an E8 Torx
®socket.
8. Turn the vertical aiming screw until the headlamp beam
is aimed to the horizontal
tape line. Turn it clockwise or
counterclockwise to raise or
lower the angle of the beam.

Black plate (58,1)GMC Sierra Owner Manual - 2011
10-58 Vehicle Care
20‐Inch Tires
If your vehicle has the optional
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 9‑7
and Adding a Snow Plow
or Similar Equipment on
page 9‑125 for additional
information.
Notice: If the vehicle has
low‐profile tires, they 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 vehicle 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.
Tire Sidewall Labeling
Useful information about a
tire is molded into the sidewall.
The following illustrations are
examples of a typical P‐Metric
and a LT‐Metric tire sidewall.
Passenger (P‐Metric) Tire
(A) Tire Size:The tire size
code 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 for more detail.

Black plate (59,1)GMC Sierra Owner Manual - 2011
Vehicle Care 10-59
(B) 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.
(C) 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.
(D) Tire Identification Number
(TIN)
:The letters and numbers
following 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.
(E) Tire Ply Material
:The type
of cord and number of plies in
the sidewall and under the tread.
(F) 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 on page 10‑80.
(G) Maximum Cold Inflation
Load Limit
:Maximum load
that can be carried and the
maximum pressure needed
to support that load. For
information on recommended
tire pressure see Tire Pressure
on page 10‑66 andVehicle
Load Limits on page 9‑25.
Light Truck (LT-Metric) Tire
(A) Tire Size:The tire size
code 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 for more detail.

Black plate (61,1)GMC Sierra Owner Manual - 2011
Vehicle Care 10-61
Tire Designations
Tire Size
The following examples show
the different parts of a 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.
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 means
a light truck tire engineered to
standards set by the U.S. Tire
and Rim Association.

Black plate (62,1)GMC Sierra Owner Manual - 2011
10-62 Vehicle Care
(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 psi (pounds per
square inch) or kPa (kilopascal). Accessory Weight
:This
means 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.
Belt
:A rubber coated layer of
cords that is located 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.

Black plate (82,1)GMC Sierra Owner Manual - 2011
10-82 Vehicle Care
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
(except some aluminum wheels,
which can sometimes be repaired).
See your dealer if any of these
conditions exist.
Your dealer will know the kind of
wheel you need.
Each new wheel should have
the same load-carrying capacity,
diameter, width, offset and be
mounted the same way as the
one it replaces.
If you need to replace any of the
wheels, wheel bolts, wheel nuts
or Tire Pressure Monitor System
(TPMS) sensors, replace them only
with new GM original equipment
parts. This way, you will be sure to
have the right wheel, wheel bolts,
wheel nuts, and TPMS sensors for
the vehicle.{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.
Notice: 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. Whenever a wheel, wheel
bolt or wheel nut is replaced
on a dual wheel setup, check
the wheel nut torque after
160, 1 600 and 10 000 km
(100, 1,000 and 6,000 miles)
of driving. For proper torque,
see
“Wheel Nut Torque” under
Capacities and Specifications on
page 12‑2.
See If a Tire Goes Flat on
page 10‑84 for more information.
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.