GMC SUBURBAN 1999 Owner's Manual

4-48
Your warranty does not cover parts or components that
fail because of overloading.
The label will help you decide how much cargo and
installed equipment your truck can carry.
Using heavier suspension components to get added
durability might not change your weight ratings. Ask
your dealer to help you load your vehicle the right way.
If you put things inside your vehicle
-- like suitcases,
tools, packages, or anything else
-- they go as fast as
the vehicle goes. If you have to stop or turn quickly, or
if there is a crash, they'll keep going.
CAUTION:
Things you put inside your vehicle can strike
and injure people in a sudden stop or turn,
or in a crash.

Put things in the cargo area of your vehicle.
Try to spread the weight evenly.

Never stack heavier things, like suitcases,
inside the vehicle so that some of them are
above the tops of the seats.

Don't leave an unsecured child restraint in
your vehicle.

When you carry something inside the
vehicle, secure it whenever you can.

Don't leave a seat folded down unless you
need to.
There's also important loading information for off-road
driving in this manual. See ªLoading Your Vehicle for
Off
-Road Drivingº in the Index.

4-49 Front Axle Reserve Capacity
This is the difference between your front GAWR and
the front axle weight of your truck with full fuel and
passengers. It is the amount of weight you can add to
your front axle before reaching your front GAWR.
The front axle reserve
capacity for your vehicle
can be found in the lower
right hand corner of the
tire/certification label, as
shown in this example.
In order to calculate the amount of weight any
front accessory is adding to the front axle, use the
following formula.
(W x (A+W.B.)) / W.B.= Weight the accessory is adding
to the front axle
Where: W= Weight of added accessory
A= Distance that the accessory is
in front of the front axle
W.B.= Vehicle Wheelbase

4-50
For example, adding a 700 lb. ( 318 kg) snow plow
adds more than 700 lb. ( 318 kg) to the front axle.
Using the formula, if the snow plow is 4 ft. (122 cm)
in front of the front axle and the wheel base is
10 ft. (305 cm), then:
W= 700 lb. ( 318 kg), A= 4 ft. (122 cm) and
W.B.= 10 ft. (305 cm)
(W x (A+W.B.)) / W.B. = (700 x (4ft. + 10 ft.)) /
10 ft. = 980 lbs.
So, if your truck's front axle reserve capacity is more
than 980 lbs. (445 kg), you could add this snow plow
without exceeding the front GAWR.
You can add heavier equipment on the front of the
vehicle if you compensate for it by carrying fewer
passengers, less cargo or by positioning cargo more
towards the rear. This has the effect of reducing the
load on the front. However, the front GAWR, rear
GAWR and the GVWR must never be exceeded.Total Vehicle Reserve Capacity
This is the difference between your GVWR and the
weight of your truck with full fuel and passengers.
It is the amount of weight you can add to your vehicle
before reaching your GVWR.
The reserve capacity numbers are intended as a guide
when selecting the amount of equipment or cargo your
truck can carry. If you are unsure of your truck's front,
rear or total weight, go to a weigh station and weigh
your vehicle. Your dealer can help you with this.
Trailer Recommendations
You must subtract your hitch loads from the CWR
for your vehicle. Weigh your vehicle with the trailer
attached, so that you won't go over the GVWR or
GAWR. If you are using a weight
-distributing hitch,
weigh the vehicle without the equalizer bars in place.
You'll get the best performance if you spread out the
weight of your load the right way, and if you choose the
correct hitch and trailer brakes.
For more information, see ªTrailer Towingº in the Index.

4-51
Towing a Trailer
CAUTION:
If you don't use the correct equipment and drive
properly, you can lose control when you pull a
trailer. For example, if the trailer is too heavy,
the brakes may not work well
-- or even at all.
You and your passengers could be seriously
injured. Pull a trailer only if you have followed
all the steps in this section. Ask your dealer for
advice and information about towing a trailer
with your vehicle.
NOTICE:
Pulling a trailer improperly can damage your
vehicle and result in costly repairs not covered by
your warranty. To pull a trailer correctly, follow
the advice in this part, and see your dealer for
important information about towing a trailer
with your vehicle.
To identify what the vehicle trailering capacity is
for your vehicle, you should read the information
in ªWeight of the Trailerº that appears later in
this section.
If yours was built with trailering options, as many are,
it's ready for heavier trailers. But trailering is different
than just driving your vehicle by itself. Trailering means
changes in handling, durability and fuel economy.
Successful, safe trailering takes correct equipment,
and it has to be used properly.
That's the reason for this part. In it are many
time
-tested, important trailering tips and safety rules.
Many of these are important for your safety and that of
your passengers. So please read this section carefully
before you pull a trailer.

4-52 If You Do Decide To Pull A Trailer
If you do, here are some important points:

There are many different laws, including speed limit
restrictions, having to do with trailering. Make sure
your rig will be legal, not only where you live but
also where you'll be driving. A good source for this
information can be state or provincial police.

Consider using a sway control if your trailer will
weigh less than the capacity stamped on your step
bumper. You should always use a sway control if
your trailer will weigh more than the capacity
stamped on your step bumper. You can ask a
hitch dealer about sway controls.

Consider using a sway control. You can ask a
hitch dealer about sway controls.

Don't tow a trailer at all during the first 500 miles
(800 km) your new vehicle is driven. Your engine,
axle or other parts could be damaged.

Then, during the first 500 miles (800 km) that you
tow a trailer, don't drive over 50 mph (80 km/h) and
don't make starts at full throttle. This helps your
engine and other parts of your vehicle wear in at the
heavier loads.
You should tow in DRIVE (D). You may want to
shift the transmission to THIRD (3) or, if necessary,
a lower gear selection if the transmission shifts too
often (e.g., under heavy loads and/or hilly conditions).
If you have a manual transmission and you are towing
a trailer, it's better not to use FIFTH (5) gear. Just
drive in FOURTH (4) gear (or, as you need to, a
lower gear). See ªTow/Haul Modeº in the Index.
Three important considerations have to do with weight:

the weight of the trailer,

the weight of the trailer tongue

and the weight on your vehicle's tires.
Tow/Haul Mode
Tow/haul is a feature that assists when pulling a heavy
trailer or a large or heavy load. The purpose of the
tow/haul mode is to:

Reduce the frequency and improve the predictability
of transmission shifts when pulling a heavy trailer or
a large or heavy load.

Provide the same solid shift feel when pulling a
heavy trailer or a large or heavy load as when the
vehicle is unloaded.

Improve control of vehicle speed while requiring less
throttle pedal activity when pulling a heavy trailer or
a large or heavy load.

4-53
Your vehicle is equipped with a button at the end of
the shift lever which, when pressed, enables tow/haul.
Your vehicle may be equipped with Autoride which
further improves your vehicle's ride while towing.
See ªAutorideº in the Index for more information.
When the button is pressed, a light on the instrument
panel will illuminate to indicate that tow/haul has been
selected. Tow/haul may be turned off by pressing the
button again, at which time the indicator light on
the instrument panel will turn off. The vehicle will
automatically turn off tow/haul every time it is started.
Tow/haul is designed to be most effective when the vehicle
and trailer combined weight is at least 75% of the vehicle's
Gross Combined Weight Rating (GCWR). Tow/haul is
most useful under the following driving conditions:

When pulling a heavy trailer or a large or heavy load
through rolling terrain.

When pulling a heavy trailer or a large or heavy load
in stop and go traffic.

When pulling a heavy trailer or a large or heavy load
in busy parking lots where improved low speed
control of the vehicle is desired.
Operating the vehicle in tow/haul when lightly loaded
or with no trailer at all will not cause damage. However,
there is no benefit to the selection of tow/haul when the
vehicle is unloaded. Such a selection when unloaded may result in
unpleasant engine and transmission driving
characteristics and reduced fuel economy. Tow/haul is
recommended only when pulling a heavy trailer or a
large or heavy load.
Weight of the Trailer
How heavy can a trailer safely be?
It depends on how you plan to use your rig. For example,
speed, altitude, road grades, outside temperature and
how much your vehicle is used to pull a trailer are all
important. And, it can also depend on any special
equipment that you have on your vehicle.
Use one of the following charts to determine how much
your vehicle can weigh, based upon your vehicle model
and options.
Maximum trailer weight is calculated assuming only the
driver is in the tow vehicle and it has all the required
trailering equipment. The weight of additional optional
equipment, passengers and cargo in the tow vehicle
must be subtracted from the maximum trailer weight.
The engine oil cooler and the heavy
-duty trailering
package is required on C/K
-2500 models with the
VORTEC 6000 engine.

4-54
C-1500 (2WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
4800 V8 3.42 6,100 lbs. (2 767 kg)
3.73 7,100 lbs. (3 221 kg)
5300 V8 3.42 7,100 lbs. (3 221 kg)
3.73 8,100 lbs. (3 674 kg)
5300 V8 3.73 8,000 lbs. (3 629 kg)
(Suburban/
Yukon XL)4.10 9,000 lbs. (4 082 kg)
* Weight
-distributing hitch tongue weight 10% to 15%
of hitch pulling weight 1,200 lbs. (544 kg) maximum.K
-1500 (4WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
4800 V8 3.73 6,800 lbs. (3 084 kg)
4.10 7,800 lbs. (3 538 kg)
5300 V8 3.73 7,800 lbs. (3 538 kg)
4.10 8,800 lbs. (3 992 kg)
5300 V8 3.73 7,800 lbs. (3 538 kg)
(Suburban/
Yukon XL)4.10 8,800 lbs. (3 992 kg)
* Weight
-distributing hitch tongue weight 10% to 15%
of hitch pulling weight 1,200 lbs. (544 kg) maximum.

4-55
C-2500 LD (2WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
6000 V8 3.73 8,500 lbs. (3 856 kg)
(Suburban/
Yukon XL)4.10 10,500 lbs. (4 763 kg)
* Weight
-distributing hitch tongue weight 10% to 15%
of hitch pulling weight 1,200 lbs. (544 kg) maximum.K
-2500 HD (4WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
6000 V8 3.73 8,100 lbs. (3 674 kg)
(Suburban/
Yukon XL)4.10 10,100 lbs. (4 581 kg)
* Weight
-distributing hitch tongue weight 10% to 15%
of hitch pulling weight 1,200 lbs. (544 kg) maximum.
You can ask your dealer for our trailering information or
advice, or you can write us at the address listed in your
Warranty and Owner Assistance Information Booklet.
In Canada, write to:
General Motors of Canada Limited
Customer Communication Centre
1908 Colonel Sam Drive
Oshawa, Ontario L1H 8P7

4-56 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. 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. See ªLoading
Your Vehicleº in the Index for more information about
your vehicle's maximum load capacity.
If you're using a weight-carrying or a weight-distributing
hitch, the trailer tongue weight (A) should be 10 percent
to 15 percent of the total loaded trailer weight (B).
Do not exceed the maximum allowable tongue weight
for your vehicle.
After you've loaded your trailer, weigh the trailer and
then the tongue, separately, to see if the weights are
proper. If they aren't, you may be able to get them
right simply by moving some items around in the trailer.
Total Weight on Your Vehicle's Tires
Be sure your vehicle's tires are inflated to the upper
limit for cold tires. You'll find these numbers on the
Certification label at the rear edge of the driver's door or
see ªTire Loadingº in the Index. Then be sure you
don't go over the GVW limit for your vehicle, including
the weight of the trailer tongue.

4-57 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.
Here are some rules to follow:

If you use a step
-bumper hitch, your bumper could
be damaged in sharp turns. Make sure you have
ample room when turning to avoid contact between
the trailer and the bumper.

If you'll be pulling a trailer that, when loaded, will
weigh more than the capacity stamped on your
step bumper, 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
you're driving.
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.
For trailers up to 5,000 lbs. (2 270 kg) you may
attach the safety chains to the attaching points on the
bumper. For heavier trailers, follow the trailer or hitch
manufacturer's recommendation for attaching safety
chains. If you have the factory
-installed trailering
package, for vehicles equipped to pull a trailer up to
10,500 lbs. (4 763 kg), you may attach the safety chains
to the attaching point on the hitch platform. Always
leave just enough slack so you can turn with your rig.
Never allow safety chains to drag on the ground.