2008 GMC SIERRA Owner's Manual

C-3500 Crew
Cab (2WD)*Axle Ratio Maximum Trailer Weight GCWR**
6.0L V83.73
4.109,600 lbs (4 354 kg)
12,100 lbs (5 488 kg)16,000 lbs (7 257 kg)
18,500 lbs (8 391 kg)
6.0L V8
(Dual Rear Wheels)3.73
4.109,300 lbs (4 218 kg)
11,800 lbs (5 352 kg)16,000 lbs (7 257 kg)
18,500 lbs (8 391 kg)
*Fifth-wheel or gooseneck kingpin weight should be 15 percent to 25 percent of trailer weight up to
3,500 lbs (1 587 kg) maximum.
*Trailer rating limited to 13,000 lbs (5 897 kg) with weight distributing hitch.
**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 your vehicle should not be
exceeded.
K-3500 Regular
Cab (4WD)*Axle Ratio Maximum Trailer Weight GCWR**
6.0L V83.73
4.109,900 lbs (4 490 kg)
12,400 lbs (5 624 kg)16,000 lbs (7 257 kg)
18,500 lbs (8 391 kg)
6.0L V8
(Dual Rear Wheels)3.73
4.109,700 lbs (4 400 kg)
12,200 lbs (5 534 kg)16,000 lbs (7 257 kg)
18,500 lbs (8 391 kg)
*Fifth-wheel or gooseneck kingpin weight should be 15 percent to 25 percent of trailer weight up to
3,500 lbs (1 587 kg) maximum.
*Trailer rating limited to 13,000 lbs (5 897 kg) with weight distributing hitch.
**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 your vehicle should not be
exceeded.
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K-3500 Extended
Cab (4WD)* Axle RatioMaximum Trailer Weight GCWR**
6.0L V83.73
4.109,500 lbs (4 309 kg)
12,000 lbs (5 443 kg)16,000 lbs (7 257 kg)
18,500 lbs (8 391 kg)
6.0L V8
(Dual Rear Wheels)3.73
4.109,200 lbs (4 173 kg)
11,700 lbs (5 307 kg)16,000 lbs (7 257 kg)
18,500 lbs (8 391 kg)
*Fifth-wheel or gooseneck kingpin weight should be 15 percent to 25 percent of trailer weight up to
3,500 lbs (1 587 kg) maximum.
*Trailer rating limited to 13,000 lbs (5 897 kg) with weight distributing hitch.
**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 your vehicle should not be
exceeded.
K-3500 Crew
Cab (4WD)*Axle Ratio Maximum Trailer Weight GCWR**
6.0L V83.73
4.109,300 lbs (4 218 kg)
11,800 lbs (5 352 kg)16,000 lbs (7 257 kg)
18,500 lbs (8 391 kg)
6.0L V8
(Dual Rear Wheels)3.73
4.109,100 lbs (4 128 kg)
11,600 lbs (5 262 kg)16,000 lbs (7 257 kg)
18,500 lbs (8 391 kg)
*Fifth-wheel or gooseneck kingpin weight should be 15 percent to 25 percent of trailer weight up to
3,500 lbs (1 587 kg) maximum.
*Trailer rating limited to 13,000 lbs (5 897 kg) with weight distributing hitch.
**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 your vehicle should not be
exceeded.
Ask your dealer/retailer for our trailering information or
advice, or write us at our Customer Assistance Offices.SeeCustomer Assistance Offices on page 7-5for more
information.
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Weight of the Trailer Tongue
The tongue load (A) of any trailer is an important weight
to measure because it affects the total or gross weight
of your vehicle. The Gross Vehicle Weight (GVW)
includes the curb weight of the vehicle, any cargo you
may carry in it, and the people who will be riding in
the vehicle. If you have a lot of options, equipment,
passengers or cargo in your vehicle, it will reduce the
tongue weight your vehicle can carry, which will
also reduce the trailer weight your vehicle can tow. And
if you will tow a trailer, you must add the tongue load
to the GVW because your vehicle will be carrying
that weight, too. SeeLoading Your Vehicle on page 4-36
for more information about your vehicle’s maximum
load capacity.The trailer tongue weight (A) should be 10 percent to
15 percent of the total loaded trailer weight, up to a
maximum of 600 lbs (272 kg) for the 1500 or 2500 series,
and up to a maximum of 750 lbs (340 kg) for the 2500 HD
or 3500 series with a weight carrying hitch. The trailer
tongue weight (A) should be 10 percent to 15 percent
of the total loaded trailer weight, up to a maximum of
1,000 lbs (453 kg) for the 1500 series and up to a
maximum of 1,500 lbs (680 kg) for the 2500, 2500 HD or
3500 series with a weight distributing hitch.
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Fifth wheel or gooseneck kingpin weight should be
15 to 25 percent of the trailer weight up to the maximum
amount specied in the trailering chart for your vehicle.
See “Weight of the Trailer”, and “Fifth-Wheel and
Gooseneck Trailering” in this section.
Do not exceed the maximum allowable tongue weight
for your 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.
After you have loaded the trailer, weigh the trailer and
then the tongue separately, to see if the weights
are proper. If they are not, you may be able to get them
right by moving some items around in the trailer.
Trailering may be limited by the vehicle’s ability to carry
tongue weight. Tongue weight cannot cause the
vehicle to exceed the GVWR (Gross Vehicle Weight
Rating) or the RGAWR (Rear Gross Axle Weight
Rating). The effect of additional weight may reduce
your trailering capacity more than the total of the
additional weight.Consider the following example:
A vehicle model base weight is 5,500 lbs (2 495 kg);
2,800 lbs (1 270 kg) at the front axle and 2,700 lbs
(1 225 kg) at the rear axle. It has a GVWR of 7,200 lbs
(3 266 kg), a RGAWR of 4,000 lbs (1 814 kg) and a
GCWR (Gross Combination Weight Rating) of
14,000 lbs (6 350 kg). The trailer rating should be:
You can expect tongue weight to be at least 10 percent of
trailer weight (850 lbs (386 kg)) and because the weight
is applied well behind the rear axle, the effect on the rear
axle will be greater than just the weight itself, as much as
1.5 times as much. The weight at the rear axle could be
850 lbs (386 kg) X 1.5 = 1,275 lbs (578 kg). Since the
rear axle already weighs 2,700 lbs (1 225 kg), adding
1,275 lbs (578 kg) brings the total to 3,975 lbs (1 803 kg).
This is very close to, but within the limit for RGAWR
as well. The vehicle is set to trailer up to
8,500 lbs (3 856 kg).
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But let’s say your specic vehicle is equipped with some
of the latest options and you have a front seat passenger
and two rear seat passengers with some luggage and
gear in the vehicle as well. You may add 300 lbs (136 kg)
to the front axle weight and 400 lbs (181 kg) to the rear
axle weight. Your vehicle now weighs:
Weight is still below 7,200 lbs (3 266 kg) and you may
think that you should subtract 700 additional pounds
(318 kg) from your trailering capacity to stay within
GCWR limits. Your maximum trailer would only be
7,800 lbs (3 538 kg). You may go further and think you
must limit tongue weight to less than 1,000 lbs (454 kg) to
avoid exceeding GVWR. But, you must still consider the
effect on the rear axle. Because your rear axle now
weighs 3,100 lbs (1 406 kg), you can only put 900 lbs
(408 kg) on the rear axle without exceeding RGAWR.The effect of tongue weight is about 1.5 times the actual
weight. Dividing the 900 lbs (408 kg) by 1.5 leaves you
with being able to handle only 600 lbs (272 kg) of tongue
weight. Since tongue weight is usually at least 10 percent
of total loaded trailer weight, you can expect that the
largest trailer your vehicle can properly handle is
6,000 lbs (2 721 kg).
It is important that you make sure your vehicle does not
exceed any of its ratings — GCWR, GVWR, RGAWR,
Maximum Trailer Rating or Tongue Weight. The
only way to be sure you are not exceeding any of these
ratings is to weigh your vehicle and trailer.
Total Weight on Your Vehicle’s Tires
Be sure your vehicle’s tires are inated to the upper limit
for cold tires. You’ll nd these numbers on the
Certication label at the rear edge of the driver’s door or
see Loading Your Vehicle for more information. Then
be sure you don’t go over the GVW limit for your vehicle,
or the GAWR, including the weight of the trailer
tongue. If you use a weight distributing hitch, make sure
you don’t go over the rear axle limit before you apply
the weight distribution spring bars.
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Hitches
It’s important to have the correct hitch equipment.
Crosswinds, large trucks going by and rough roads are
a few reasons why you’ll need the right hitch.
Weight-Distributing Hitches and Weight
Carrying Hitches
A:Body to Ground Distance
B:Front of VehicleWhen using a weight-distributing hitch, the hitch must
be adjusted so the distance (A) remains the same both
before and after coupling the trailer to the tow vehicle.
If you use a step-bumper hitch, 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.
If you will be pulling a trailer that, when loaded, will
weigh more than 5,000 lbs (2 270 kg) be sure to use a
properly mounted weight-distributing hitch and sway
control of the proper size. This equipment is very
important for proper vehicle loading and good handling
when driving. Always use a sway control if the trailer
will weigh more than these limits. You can ask a
hitch dealer about sway controls.
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 percent of the trailer weight up to the maximum
amount specied in the trailering chart for your vehicle.
See “Weight of the Trailer” in this section for more
information.
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The hitch should be located in the pickup bed so that it’s
centerline is over or slightly in front of the rear axle. Take
care that it is not so far 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
fth wheel hitch assemblies can help this condition. There
should be at least six inches 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
You should always attach chains between your vehicle
and your 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 you
are towing a trailer up to 5,000 lbs (2 271 kg) with a
factory-installed step bumper, you may attach the safety
chains to the attaching points on the bumper. If you are
towing a trailer up to your vehicle’s trailer rating limit you
may attach the safety chains to the attaching point on the
hitch platform. If you are towing with an aftermarket hitch
follow the trailer or hitch manufacturer’s recommendation
for attaching safety chains. Always leave just enough
slack so you can turn with your rig. Never allow safety
chains to drag on the ground.
Trailer Brakes
If your trailer weighs more than 2,000 lbs (900 kg)
loaded, then it needs its own brakes – and they must be
adequate. Be sure to read and follow the instructions
for the trailer brakes so you’ll be able to install,
adjust and maintain them properly.
If your vehicle is equipped with StabiliTrak
®, your trailer
cannot tap into the vehicle’s hydraulic brake system.
Your trailer brake system can tap into the vehicle’s
hydraulic brake system only if:
The trailer parts can withstand 3,000 psi
(20 650 kPa) of pressure.
The trailer’s brake system will use less than
0.02 cubic inch (0.3 cc) of uid from your vehicle’s
master cylinder. Otherwise, both braking systems
won’t work well. You could even lose your brakes.
If everything checks out this far, make the brake tap at
the port on the master cylinder that sends the uid
to the rear brakes. But don’t use copper tubing for this.
If you do, it will bend and nally break off. Use steel
brake tubing.
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Integrated Trailer Brake Control
System
Your vehicle may have an
Integrated Trailer Brake
Control (ITBC) system for
electric trailer brakes.
This symbol is located on the Trailer Brake Control
Panel on vehicles with an Integrated Trailer Brake
Control System. The power output to the trailer brakes
is based on the amount of brake pressure being
applied by your vehicle’s brake system. This available
power output to the trailer brakes can be adjusted
to a wide range of trailering situations.The ITBC system is integrated with your vehicle’s brake,
anti-lock brake and StabiliTrak
®(if equipped) systems.
In trailering conditions that cause your vehicle’s anti-lock
brake or StabiliTrak
®systems to activate, power sent
to the trailer’s brakes will be automatically adjusted
to minimize trailer wheel lock-up. This does not imply
that your trailer has the StabiliTrak
®system.
If your vehicle’s brake, anti-lock brake or StabiliTrak
®
systems are not functioning properly, your ITBC system
may not be fully functional or may not function at all.
Make sure all of these systems are fully operational to
ensure full functionality of the ITBC system.
The ITBC system is powered through your vehicle’s
electrical system. Turning the ignition off will also turn off
the ITBC system. The ITBC system is fully functional
only when the ignition is in ON or in RUN.
The ITBC system can only be used with trailers with
electric brakes.
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