2009 HUMMER H3 weight

Weight of the Trailer Tongue
The tongue load (A) of any trailer is
an important weight to measure
because it affects the total gross
weight of the vehicle. 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.If
there are a lot of options, equipment,
passengers or cargo in the vehicle,
it will reduce the tongue weight
the vehicle can carry, which will also
reduce the trailer weight the
vehicle can tow. If towing a trailer,
the tongue load must be added
to the GVW because the vehicle will
be carrying that weight, too. See
Loading the Vehicle on page 4-35
for more information about the
vehicle’s maximum load capacity.The trailer tongue weight (A) should
be 10 percent to 15 percent of
the total loaded trailer weight (B), up
to a maximum of 500 lbs (227 kg)
with a weight carrying hitch or
a weight distributing hitch.
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.If the spare tire carrier is mounted
on the back of the vehicle and
the hitch extension is too short,
the spare tire may interfere
with trailer coupling or trailer tongue
jack operation on some types of
trailers.
After loading the trailer, weigh the
trailer and then the tongue,
separately, to see if the weights are
proper. If they aren’t, adjustments
might be made by moving some
items around in the trailer.
Driving Your Vehicle 4-45

Total Weight on the Vehicle’s
Tires
Be sure the vehicle’s tires are
inated to the upper limit for cold
tires. These numbers can be found
on the Certication/Tire Label
located on the B-pillar below the
door latch or seeLoading the
Vehicle on page 4-35. Make sure
not to go over the GVW limit for the
vehicle, or the GAWR, including
the weight of the trailer tongue. If
using a weight distributing hitch,
make sure not to go over the rear
axle limit before applying the weight
distribution spring bars.
Hitches
It is important to have the correct
hitch equipment. Crosswinds,
large trucks going by and rough
roads are a few reasons why
the right hitch is needed.Weight-Distributing Hitches and
Weight Carrying Hitches
When using a weight-distributing
hitch, the hitch must be adjusted so
that the distance (A) remains the
same both before and after coupling
the trailer to the tow vehicle.
Trailering may also 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 can reduce the
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:
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 (A) Body-to-Ground Distance (B)
Front of Vehicle
4-46 Driving Your Vehicle

rear axle, the effect on the
rear axle is 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).If the vehicle has many options and
there is a front seat passenger
and two rear seat passengers with
some luggage and gear in the
vehicle as well, 300 lbs (136 kg)
could be added to the front
axle weight and 400 lbs (181 kg) to
the rear axle weight. The vehicle
now weighs:
Weight is still below 7,200 lbs
(3 266 kg) and you might think
700 additional pounds (318 kg)
should be subtracted from the
trailering capacity to stay within
GCWR limits. The maximum trailer
would only be 7,800 lbs (3 538 kg).
You may go further and think
the tongue weight should be limitedto less than 1,000 lbs (454 kg) to
avoid exceeding GVWR. But
the effect on the rear axle must still
be considered. Because the rear
axle now weighs 3,100 lbs
(1 406 kg), 900 lbs (408 kg) can be
put 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 only
600 lbs (272 kg) of tongue weight
that can be handled. Since
tongue weight is usually at least
10 percent of total loaded trailer
weight, expect that the largest trailer
the vehicle can properly handle is
6,000 lbs (2 721 kg).
It is important that the vehicle
does not exceed any of its
ratings — GCWR, GVWR, RGAWR,
Maximum Trailer Rating or
Tongue Weight. The only way
to be sure it is not exceeding any of
these ratings is to weigh the vehicle
and trailer.
Driving Your Vehicle 4-47

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. Always leave just enough
slack so the rig can turn. Never
allow safety chains to drag on the
ground.
Trailer Brakes
A loaded trailer that weighs more
than 1,500 lbs (680 kg) 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.
Driving with a Trailer
Towing a trailer requires a certain
amount of experience. Get to
know the rig before setting out for
the open road. Get acquainted
with the feel of handling and braking
with the added weight of the
trailer. And always keep in mind that
the vehicle you are driving is now
longer and not as responsive as the
vehicle is by itself.
Before starting, check all trailer hitch
parts and attachments, safety
chains, electrical connectors, lamps,
tires and mirror adjustments. If
the trailer has electric brakes, start
the vehicle and trailer moving
and then apply the trailer brake
controller by hand to be sure
the brakes are working. This checks
the electrical connection at the
same time.
During the trip, check occasionally
to be sure that the load is secure,
and that the lamps and any
trailer brakes are still working.
Following Distance
Stay at least twice as far behind
the vehicle ahead as you would
when driving the vehicle without a
trailer. This can help to avoid
situations that require heavy braking
and sudden turns.
Passing
More passing distance is needed
when towing a trailer. Because
the rig is longer, it is necessary to
go much farther beyond the
passed vehicle before returning to
the lane.
Backing Up
Hold the bottom of the steering
wheel with one hand. Then, to move
the trailer to the left, move that
hand to the left. To move the trailer
to the right, move your hand to
the right. Always back up slowly
and, if possible, have someone
guide you.
4-48 Driving Your Vehicle

Trailer Brake Control Wiring
Harness
The trailer brake control wiring
harness is located under the
instrument panel to the right of the
steering column. The wires are
taped to the harness that goes to
the courtesy light under the
instrument panel. The harness has
the following wires:
Red Wire: AUX B+
Black Wire: Ground
Light Blue Wire: Brake Signal
Dark Blue Wire: Trailer Brakes
Trailer Recommendations
Subtract the hitch loads from the
Cargo Weight Rating (CWR). CWR
is the maximum weight of the
load the vehicle can carry. It does
not include the weight of the people
inside, but you can gure about
150 lbs. (68 kg) for each passenger.
The total cargo load must not be
more than the vehicles CWR.
Weigh the vehicle with the trailer
attached, so the GVWR or GAWR
are not exceeded. If using a
weight-distributing hitch, weigh the
vehicle without the spring bars
in place.
The best performance is obtained
by correctly spreading out the weight
of the load and choosing the
correct hitch and trailer brakes.
For more information seeTowing a
Trailer on page 4-42.
Driving Your Vehicle 4-53

(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) Service Description
:The service description indicates
the load range and speed
rating of a tire. The load index
can range from 1 to 279. Speed
ratings range from A to Z.
Tire Terminology and
Denitions
Air Pressure:The amount of
air inside the tire pressing
outward on each square inch
of the tire. Air pressure is
expressed in pounds per square
inch (psi) or kilopascal (kPa).
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.
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 pounds per
square inch (psi) or kilopascals
(kPa) before a tire has built
up heat from driving. See
Inflation - Tire Pressure on
page 5-51.
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.
5-48 Service and Appearance Care

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 Identication
Number (TIN), an alphanumeric
designator which can also
identify the tire manufacturer,
production plant, brand, and date
of production.
GVWR
:Gross Vehicle Weight
Rating. SeeLoading the Vehicle
on page 4-35.
GAWR FRT
:Gross Axle
Weight Rating for the front axle.
SeeLoading the Vehicle on
page 4-35.
GAWR RR
:Gross Axle
Weight Rating for the rear axle.
SeeLoading the Vehicle on
page 4-35.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 Ination Pressure
:The maximum air pressure
to which a cold tire can be
inated. The maximum air
pressure is molded onto the
sidewall.
Maximum Load Rating
:The load rating for a tire at the
maximum permissible ination
pressure for that tire.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 150 lbs (68 kg).
SeeLoading the Vehicle
on page 4-35.
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.
Service and Appearance Care 5-49

Passenger (P-Metric) Tire:A tire used on passenger cars
and some light duty trucks
and multipurpose vehicles.
Recommended Ination
Pressure
:Vehicle
manufacturer’s recommended
tire ination pressure as
shown on the tire placard.
SeeInflation - Tire Pressure on
page 5-51andLoading the
Vehicle on page 4-35.
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 1/16 inch
(1.6 mm) of tread remains.
SeeWhen It Is Time for New
Tires on page 5-58.
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. SeeUniform Tire Quality
Grading on page 5-62.Vehicle Capacity Weight
:The number of designated
seating positions multiplied
by 150 lbs (68 kg) plus the rated
cargo load. SeeLoading the
Vehicle on page 4-35.
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’s
capacity weight and the
original equipment tire size
and recommended ination
pressure. See “Tire and
Loading Information Label”
underLoading the Vehicle
on page 4-35.
5-50 Service and Appearance Care