2015 GMC SIERRA tow

Black plate (71,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-71
7. Stop and have someone pick upand store the chocks.
Maintenance when Trailer
Towing
The vehicle needs service more
often when pulling a trailer. See
Maintenance Schedule on
page 11-3. Things that are
especially important in trailer
operation are automatic
transmission fluid, engine oil, axle
lubricant, belts, cooling system, and
brake system. It is a good idea to
inspect these before and during
the trip.
Check periodically to see that all
hitch nuts and bolts are tight.
Trailer Towing
If the vehicle has a diesel engine,
see the Duramax diesel
supplement.
If the vehicle is bi-fuel, see the
bi-fuel supplement. Do not tow a trailer during break-in.
See
New Vehicle Break-In on
page 9-23 for more information.
{Warning
The driver can lose control when
pulling a trailer if the correct
equipment is not used or the
vehicle is not driven properly. For
example, if the trailer is too
heavy, the brakes may not work
well or even at all. The driver and
passengers could be seriously
injured. The vehicle may also be
damaged; the resulting repairs
would not be covered by the
vehicle warranty. Pull a trailer
only if all the steps in this section
have been followed. Ask your
dealer for advice and information
about towing a trailer with the
vehicle.
{Caution
Pulling a trailer improperly can
damage the vehicle and result in
costly repairs not covered by the
vehicle warranty. To pull a trailer
correctly, follow the advice in this
section and see your dealer for
important information about
towing a trailer with the vehicle.
See Vehicle Load Limits on
page 9-15 for more information
about the vehicle's maximum load
capacity.
To identify the trailering capacity of
the vehicle, read the information in
“Weight of the Trailer” later in this
section.

Black plate (72,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-72 Driving and Operating
Trailering is different than just
driving the vehicle by itself.
Trailering means changes in
handling, acceleration, braking,
durability, and fuel economy.
Successful, safe trailering takes
correct equipment, and it has to be
used properly.
The following information has many
time-tested, important trailering tips
and safety rules. Many of these are
important for your safety and that of
your passengers. Read this section
carefully before pulling a trailer.
Weight of the Trailer
How heavy can a trailer safely be?
It depends on how the rig is used.
Speed, altitude, road grades,
outside temperature, and how much
the vehicle is used to pull a trailer
are all important. It can depend on
any special equipment on the
vehicle, and the amount of tongueweight the vehicle can carry. See
“Weight of the Trailer Tongue”
later
in this section for more information.
Trailer weight rating (TWR) for 1500
series trucks is calculated assuming
the tow vehicle has the driver, a
front seat passenger, and all
required trailering equipment.
Weight of additional optional
equipment, passengers, and cargo
in the tow vehicle must be
subtracted from the trailer weight
rating.
Trailer weight rating (TWR) for
2500 and 3500 series trucks is
calculated assuming the tow vehicle
has only the driver but all required
trailering equipment. Weight of
additional optional equipment,
passengers, and cargo in the tow
vehicle must be subtracted from the
trailer weight rating. Ask your dealer for trailering
information or advice.
For kingpin weight and trailer
tongue weight information, see
“Weight of the Trailer Tongue”
later
in this section.
Use the following chart to determine
how much the vehicle can weigh,
based upon the vehicle model and
options.
Weights listed apply for
conventional trailers and fifth-wheel
trailers unless otherwise noted.

Black plate (75,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-75
VehicleAxle Ratio Maximum Trailer Weight GCWR (a)
6.0L V8 –Conventional Trailer 4.105 897 kg (13,000 lb) 9 299 kg (20,500 lb)
6.0L V8 –Fifth-Wheel Trailer 4.106 305 kg (13,900 lb) 9 299 kg (20,500 lb)
3500 Series 4WD Crew Cab Long Box 6.0L V8 (Single Rear Wheels) 3.734 173 kg (9,200 lb) 7 257 kg (16,000 lb)
6.0L V8 (Single Rear Wheels)
Conventional Trailer 4.10
5 897 kg (13,000 lb) 9 299 kg (20,500 lb)
6.0L V8 (Single Rear Wheels)
Fifth-Wheel Trailer 4.10
6 214 kg (13,700 lb) 9 299 kg (20,500 lb)
6.0L V8 (Dual Rear Wheels) 3.733 992 kg (8,800 lb) 7 257 kg (16,000 lb)
6.0L V8 (Dual Rear Wheels) 4.106 033 kg (13,300 lb) 9 299 kg (20,500 lb)
(a) The Gross Combination Weight Rating (GCWR) is the total allowable weight of the completely loaded vehicle
and trailer including any passengers, cargo, equipment, and conversions. The GCWR for the vehicle should not be
exceeded.
(b) This model is neither designed nor intended to tow fifth-wheel or gooseneck trailers.
Ask your dealer for trailering information or advice.

Black plate (76,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-76 Driving and Operating
Weight of the Trailer Tongue
The tongue load (1) of any trailer is
very important because it is also
part of the vehicle weight. The
Gross Vehicle Weight (GVW)
includes the curb weight of the
vehicle, any cargo carried in it, and
the people who will be riding in the
vehicle as well as trailer tongue
weight. Vehicle options, equipment,
passengers and cargo in the vehicle
reduce the amount of tongue weight
the vehicle can carry, which will also
reduce the trailer weight the vehicle
can tow.
Trailer tongue weight (1) should be
10–15% and fifth-wheel or
gooseneck kingpin weight should be
15–25% of the loaded trailer
weight (2) up to the maximums for
vehicle series and hitch type.

Black plate (77,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-77
Vehicle Series Hitch TypeMaximum Tongue
Weight
1500 Weight-Carrying 363 kg (800 lb)
1500 Weight-Distributing 544 kg (1,200 lb)
2500/3500
Standard Box Weight-Carrying or
Weight-Distributing 680 kg (1,500 lb)
2500/
3500 Long Box Weight-Carrying or
Weight-Distributing 907 kg (2,000 lb)
2500 Fifth-Wheel Gooseneck 1 361 kg (3,000 lb)
3500 Single Rear
Wheels Fifth-Wheel Gooseneck 1 814 kg (4,000 lb)
3500 Dual Rear
Wheels Fifth-Wheel Gooseneck 2 495 kg (5,500 lb)
Do not exceed the maximum
allowable tongue weight for the
vehicle. Choose the shortest hitch
extension that will position the hitch
ball closest to the vehicle. This will
help reduce the effect of trailer
tongue weight on the rear axle. Trailer rating may be limited by the
vehicle's ability to carry tongue
weight. Tongue or kingpin weight
cannot cause the vehicle to exceed
the GVWR (Gross Vehicle Weight
Rating) or the RGAWR (Rear Gross
Axle Weight Rating). See
“Total
Weight on the Vehicle's Tires” later
in this section. After loading the trailer, weigh the
trailer and then the tongue,
separately, to see if the weights are
proper. If they are not, adjustments
might be made by moving some
items around in the trailer.
If a cargo carrier is used in the
trailer hitch receiver, choose a
carrier that positions the load as
close to the vehicle as possible.
Make sure the total weight,
including the carrier, is no more than
half of the maximum allowable
tongue weight for the vehicle or
227 kg (500 lb), whichever is less.
Total Weight on the Vehicle's
Tires
Be sure the vehicle's tires are
inflated to the inflation pressures
found on the Certification/Tire label
on the center pillar or see
Vehicle
Load Limits on page 9-15. Make
sure not to exceed the GVWR limit
for the vehicle, or the RGAWR, with
the tow vehicle and trailer fully
loaded for the trip including the
weight of the trailer tongue. If using

Black plate (78,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-78 Driving and Operating
a weight-distributing hitch, make
sure not to exceed the RGAWR
before applying the weight
distribution spring bars.
Weight of the Trailering
Combination
It is important that the combination
of the tow vehicle and trailer does
not exceed any of its weight
ratings—GCWR, GVWR, RGAWR,
Trailer Weight Rating, or Tongue
Weight. The only way to be sure it is
not exceeding any of these ratings
is to weigh the tow vehicle and
trailer combination, fully loaded for
the trip, getting individual weights
for each of these items.
Towing Equipment
Hitches
The correct hitch equipment helps
maintain combination control. Many
trailers can be towed with a
weight-carrying hitch which simply
features a coupler latched to the
hitch ball, or a tow eye latched to a
pintle hook. Other trailers may
require a weight-distributing hitch
that uses spring bars to distribute
the trailer tongue weight among the
two vehicle and trailer axles.
Fifth-wheel and gooseneck hitches
may also be used. See “Weight of
the Trailer Tongue” underTrailer
Towing on page 9-71 for rating limits
with various hitch types. If a step-bumper hitch will be used,
the bumper could be damaged in
sharp turns. Make sure there
is ample room when turning to avoid
contact between the trailer and the
bumper.
Consider using sway controls with
any trailer. Ask a trailering
professional about sway controls or
refer to the trailer manufacturer's
recommendations and instructions.
Weight-Distributing Hitch and
Adjustment
A weight distributing hitch may be
useful with some trailers. Use the
following guidelines to determine if a
weight distributing hitch should
be used.

Black plate (79,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Driving and Operating 9-79
Vehicle SeriesTrailer WeightWeight Distributing Hitch
Usage Hitch Distribution
1500 Up to 3175 kg (7,000 lb) OptionalRefer to trailer
manufacturer ’s
recommendation
1500 Over 3175 kg (7,000 lb) Required50%
2500/3500 Up to 8165 kg (18,000 lb) OptionalRefer to trailer
manufacturer ’s
recommendation
1. Body to Ground Distance
2. Front of Vehicle
When using a weight-distributing
hitch, measure distance (1) before
coupling the trailer to the hitch ball.
Measure the height again after the
trailer is coupled and adjust the
spring bars so the distance (1) is as
close as possible to halfway
between the two measurements.
Fifth-Wheel and Gooseneck
Trailering
Fifth-wheel and gooseneck trailers
can be used with many pickup
models. These trailers place a
larger percentage of the weight (kingpin weight) on the tow vehicle
than conventional trailers. Make
sure this weight does not cause the
vehicle to exceed GAWR or GVWR.
Fifth-wheel or gooseneck kingpin
weight should be 15 to 25% of the
trailer weight up to the maximum
amount specified in the trailering
chart for the vehicle. See
“Weight of
the Trailer” underTrailer Towing on
page 9-71.
The hitch should be located in the
pickup bed so that its centerline is
over or slightly in front of the rear
axle. Take care that it is not so far

Black plate (80,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
9-80 Driving and Operating
forward that it will contact the back
of the cab in sharp turns. This is
especially important for short box
pickups. Trailer pin box extensions
and sliding fifth-wheel hitch
assemblies can help this condition.
There should be at least 15 cm (6 in)
of clearance between the top of the
pickup box and the bottom of the
trailer shelf that extends over
the box.
Make sure the hitch is attached to
the tow vehicle frame rails. Do not
use the pickup box for support.
Safety Chains
Always attach chains between the
vehicle and the trailer. Cross the
safety chains under the tongue of
the trailer to help prevent the tongue
from contacting the road if it
becomes separated from the hitch.
Instructions about safety chains
may be provided by the hitch
manufacturer or by the trailer
manufacturer. If the trailer being
towed weighs up to 2 271 kg
(5,000 lb) with a factory-installedstep bumper, safety chains may be
attached to the attaching points on
the bumper; otherwise, safety
chains should be attached to holes
on the trailer hitch platform. Always
leave just enough slack so the
combination can turn. Never allow
safety chains to drag on the ground.
Trailer Brakes
A loaded trailer that weighs more
than 900 kg (2,000 lb) needs to have
its own brake system that is
adequate for the weight of the
trailer. Be sure to read and follow
the instructions for the trailer brakes
so they are installed, adjusted, and
maintained properly.
Do not tap into the vehicle's
hydraulic brake system.
Auxiliary Battery
The auxiliary battery provision can
be used to supply electrical power
to additional equipment that may be
added, such as a slide-in camper.
If equipped, this relay will be on the
driver side of the vehicle, next to the
underhood electrical center.
Be sure to follow the proper
installation instructions included with
any electrical equipment that is
installed.
{Caution
Leaving electrical equipment on
for extended periods will drain the
battery. Always turn off electrical
equipment when not in use and
do not use equipment that
exceeds the maximum amperage
rating of 30 amps for the auxiliary
battery provision.
Trailer Wiring Harness
The vehicle is equipped with one of
the following wiring harnesses for
towing a trailer or hauling a slide-in
camper.