
Black plate (89,1)GMC Yukon/Yukon XL Owner Manual - 2012
Driving and Operating 9-89
For example, adding a 318 kg
(700 lb) snow plow actually adds
more than 318 kg (700 lb) to the
front axle. Using the formula, if the
snow plow is 122 cm (4 ft) in front of
the front axle and the wheel base is
305 cm (10 ft), then:W = 318 kg (700 lb)
A = 122 cm (4 ft)
W.B. = 305 cm (10 ft)
(W x (A + W.B.))/W.B. =
(318 x (122 + 305))/305 = 445 kg
(980 lb)
So, if the vehicle's front axle reserve
capacity is more than 980 lbs
(445 kg), the snow plow could be
added without exceeding the
front GAWR. Heavier equipment can be added on
the front of the vehicle if it is
compensated for by carrying fewer
passengers, less cargo, or by
positioning cargo toward the rear.
This has the effect of reducing the
load on the front. However, the front
GAWR, rear GAWR, and the Gross
Vehicle Weight Rating (GVWR)
must never be exceeded.
{WARNING
On some vehicles that have
certain front mounted equipment,
such as a snow plow, it may be
possible to load the front axle to
the front gross axle weight rating
(GAWR) but not have enough
weight on the rear axle to have
(Continued)
WARNING (Continued)
proper braking performance. If the
brakes cannot work properly, you
could have a crash. To help the
brakes work properly when a
snow plow is installed, always
follow the snow plow
manufacturer or installer's
recommendation for rear ballast
to ensure a proper front and rear
weight distribution ratio, even
though the actual front weight
may be less than the front
GAWR, and the total vehicle
weight is less than the gross
vehicle weight rating (GVWR).
Maintaining a proper front and
rear weight distribution ratio is
necessary to provide proper
braking performance.

Black plate (90,1)GMC Yukon/Yukon XL Owner Manual - 2012
9-90 Driving and Operating
Total vehicle reserve capacity is the
difference between the GVWR and
the weight of the vehicle with full
fuel and passengers. It is the
amount of weight that can be added
to the vehicle before reaching
theGVWR. Keep in mind that
reserve capacity numbers are
intended as a guide when selecting
the amount of equipment or cargo
the vehicle can carry. If you are
unsure of the vehicle's front, rear,
or total weight, go to a weigh station
and weigh the vehicle. Your dealer
can also help you with this.The total vehicle reserve capacity
for the vehicle can be found in the
lower right corner of the
Certification/Tire label as shown
previously.
See your dealer for additional
advice and information about using
a snow plow on the vehicle. Also,
see
Vehicle Load Limits on
page 9‑16.Emergency Roof Lamp
Provisions
Vehicles with the RPO VYU snow
plow prep package also have an
emergency roof lamp provision
package, RPO TRW. Wiring for the
emergency roof lamp is provided
above the overhead console. See
Auxiliary Roof-Mounted Lamp on
page 6‑7 for switch location.

Black plate (53,1)GMC Yukon/Yukon XL Owner Manual - 2012
Vehicle Care 10-53
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.
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.

Black plate (54,1)GMC Yukon/Yukon XL Owner Manual - 2012
10-54 Vehicle Care
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
on page 10‑56.
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
on page 9‑16.
GAWR FRT
:Gross Axle Weight
Rating for the front axle. See
Vehicle Load Limits on
page 9‑16.
GAWR RR
:Gross Axle Weight
Rating for the rear axle. See
Vehicle Load Limits on
page 9‑16. 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.
Load Index
:An assigned
number ranging from 1 to 279
that corresponds to the load
carrying capacity of a tire.
Maximum Inflation Pressure
:
The maximum air pressure to
which a cold tire can be inflated.
The maximum air pressure is
molded onto the sidewall.
Maximum Load Rating
:The
load rating for a tire at the
maximum permissible inflation
pressure for that tire.

Black plate (55,1)GMC Yukon/Yukon XL Owner Manual - 2012
Vehicle Care 10-55
Maximum Loaded Vehicle
Weight
:The sum of curb
weight, accessory weight,
vehicle capacity weight, and
production options weight.
Normal Occupant Weight
:The
number of occupants a vehicle
is designed to seat multiplied by
68 kg (150 lbs). See Vehicle
Load Limits on page 9‑16.
Occupant Distribution
:
Designated seating positions.
Outward Facing Sidewall
:The
side of an asymmetrical tire that
has a particular side that faces
outward when mounted on a
vehicle. The side of the tire that
contains a whitewall, bears
white lettering, or bears
manufacturer, brand, and/or
model name molding that is
higher or deeper than the same
moldings on the other sidewall
of the tire. Passenger (P-Metric) Tire
:A
tire used on passenger cars and
some light duty trucks and
multipurpose vehicles.
Recommended Inflation
Pressure
:Vehicle
manufacturer's recommended
tire inflation pressure as shown
on the tire placard. See Tire
Pressure on page 10‑56
andVehicle Load Limits on
page 9‑16.
Radial Ply Tire
:A pneumatic
tire in which the ply cords that
extend to the beads are laid at
90 degrees to the centerline of
the tread.
Rim
:A metal support for a tire
and upon which the tire beads
are seated.
Sidewall
:The portion of a tire
between the tread and the bead. Speed Rating
:An
alphanumeric code assigned to
a tire indicating the maximum
speed at which a tire can
operate.
Traction
:The friction between
the tire and the road surface.
The amount of grip provided.
Tread
:The portion of a tire that
comes into contact with
the road.
Treadwear Indicators
:Narrow
bands, sometimes called wear
bars, that show across the tread
of a tire when only 1.6 mm
(1/16 in) of tread remains. See
When It Is Time for New Tires
on page 10‑63.

Black plate (56,1)GMC Yukon/Yukon XL Owner Manual - 2012
10-56 Vehicle Care
UTQGS (Uniform Tire Quality
Grading Standards)
:A tire
information system that
provides consumers with
ratings for a tire's traction,
temperature, and treadwear.
Ratings are determined by
tire manufacturers using
government testing procedures.
The ratings are molded into the
sidewall of the tire. See Uniform
Tire Quality Grading on
page 10‑66.
Vehicle Capacity Weight
:The
number of designated seating
positions multiplied by
68 kg (150 lbs) plus the rated
cargo load. See Vehicle Load
Limits on page 9‑16. Vehicle Maximum Load on the
Tire
:Load on an individual tire
due to curb weight, accessory
weight, occupant weight, and
cargo weight.
Vehicle Placard
:A label
permanently attached to a
vehicle showing the vehicle
capacity weight and the
original equipment tire size
and recommended inflation
pressure. See “Tire and Loading
Information Label” underVehicle
Load Limits on page 9‑16.
Tire Pressure
If the vehicle is a hybrid, see the
hybrid supplement for more
information.
Tires need the correct amount
of air pressure to operate
effectively. Notice:
Neither tire
underinflation nor
overinflation is good.
Underinflated tires, or tires
that do not have enough air,
can result in:
.Tire overloading and
overheating which could
lead to a blowout.
.Premature or
irregular wear.
.Poor handling.
.Reduced fuel economy.
Overinflated tires, or tires that
have too much air, can
result in:
.Unusual wear.
.Poor handling.
.Rough ride.
.Needless damage from
road hazards.

Black plate (57,1)GMC Yukon/Yukon XL Owner Manual - 2012
Vehicle Care 10-57
The Tire and Loading
Information label on the vehicle
indicates the original equipment
tires and the correct cold tire
inflation pressures. The
recommended pressure is the
minimum air pressure needed to
support the vehicle's maximum
load carrying capacity.
For additional information
regarding how much weight
the vehicle can carry, and an
example of the Tire and Loading
Information label, seeVehicle
Load Limits on page 9‑16. How
the vehicle is loaded affects
vehicle handling and ride
comfort. Never load the vehicle
with more weight than it was
designed to carry. When to Check
Check the tires once a month
or more.
Do not forget the spare tire.
See
Full-Size Spare Tire on
page 10‑87 for additional
information.
How to Check
Use a good quality pocket-type
gauge to check tire pressure.
Proper tire inflation cannot be
determined by looking at the tire.
Check the tire inflation pressure
when the tires are cold meaning
the vehicle has not been driven
for at least three hours or no
more than 1.6 km (1 mi). Remove the valve cap from the
tire valve stem. Press the tire
gauge firmly onto the valve to
get a pressure measurement.
If the cold tire inflation pressure
matches the recommended
pressure on the Tire and
Loading Information label, no
further adjustment is necessary.
If the inflation pressure is low,
add air until the recommended
pressure is reached. If the
inflation pressure is high, press
on the metal stem in the center
of the tire valve to release air.
Recheck the tire pressure with
the tire gauge.
Return the valve caps on the
valve stems to prevent leaks
and keep out dirt and moisture.

Black plate (64,1)GMC Yukon/Yukon XL Owner Manual - 2012
10-64 Vehicle Care
SeeTire Inspection on page 10‑62
and Tire Rotation on page 10‑62 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 conditions
including temperatures, loading
conditions, and inflation pressure
maintenance affect how fast aging
takes place. Tires will typically
need to be replaced due to wear
before they may need to be
replaced due to age. Consult the
tire manufacturer for more
information on when tires
should be replaced.
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.
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. See
Tire Sidewall Labeling on
page 10‑50 for additional
information.
GM recommends replacing all the
tires at the same time. 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. See Tire
Inspection on page 10‑62 andTire
Rotation on page 10‑62 for
information on proper tire rotation.