1999 GMC SIERRA tire size

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4-43
Loading Your Vehicle
The Certification/Tire label is found on the rear edge of
the driver's door or in the Incomplete Vehicle Document
in the cab.
The label shows the size of your original tires and the
inflation pressures needed to obtain the gross weight
capacity of your vehicle. This is called the GVWR
(Gross Vehicle Weight Rating). The GVWR includes the
weight of the vehicle, all occupants, fuel and cargo.The Certification/Tire label also tells you the maximum
weights for the front and rear axles, called Gross Axle
Weight Rating (GAWR). To find out the actual loads on
your front and rear axles, you need to go to a weigh
station and weigh your vehicle. Your dealer can help
you with this. Be sure to spread out your load equally on
both sides of the centerline.
Never exceed the GVWR for your vehicle, or the
GAWR for either the front or rear axle.
And, if you do have a heavy load, you should spread
it out.
CAUTION:
In the case of a sudden stop or collision, things
carried in the bed of your truck could shift
forward and come into the passenger area,
injuring you and others. If you put things in the
bed of your truck, you should make sure they are
properly secured.

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If you're using a weight-carrying hitch, the trailer
tongue (A) should weigh 10 percent of the total loaded
trailer weight (B). If you're using a weight
-distributing
hitch, the trailer tongue (A) should weigh 12 percent of
the total loaded trailer weight (B).
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.
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.

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6-54
CAUTION:
Rust or dirt on a wheel, or on the parts to which
it is fastened, can make wheel nuts become loose
after a time. The wheel could come off and cause
an accident. When you change a wheel, remove
any rust or dirt from places where the wheel
attaches to the vehicle. In an emergency, you can
use a cloth or a paper towel to do this; but be
sure to use a scraper or wire brush later, if
you need to, to get all the rust or dirt off.
(See ªChanging a Flat Tireº in the Index.)
When It's Time for New Tires
One way to tell when it's
time for new tires is to
check the treadwear
indicators, which will
appear when your tires have
only 1/16 inch (1.6 mm) or
less of tread remaining.
Some commercial truck
tires may not have
treadwear indicators.
You need a new tire if any of the following statements
are true:

You can see the indicators at three or more places
around the tire.

You can see cord or fabric showing through the
tire's rubber.

The tread or sidewall is cracked, cut or snagged deep
enough to show cord or fabric.

The tire has a bump, bulge or split.

The tire has a puncture, cut or other damage that
can't be repaired well because of the size or location
of the damage.

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6-55 Dual Tire Operation
When the vehicle is new, or whenever a wheel, wheel
bolt or wheel nut is replaced, check the wheel nut torque
after 100, 1,000 and 6,000 miles (160, 1 600 and
10 000 km) of driving. For proper torque, see ªWheel
Nut Torqueº in the Index.
The outer tire on a dual wheel setup generally wears
faster than the inner tire. Your tires will wear more
evenly and last longer if you rotate the tires periodically.
If you're going to be doing a lot of driving on
high
-crown roads, you can reduce tire wear by adding
5 psi (35 kPa) to the tire pressure in the outer tires.
Be sure to return to the recommended pressures when no
longer driving under those conditions. See ªChanging a
Flat Tireº in the Index for more information.
CAUTION:
If you operate your vehicle with a tire that is
badly underinflated, the tire can overheat. An
overheated tire can lose air suddenly or catch
fire. You or others could be injured. Be sure
all tires (including the spare, if any) are
properly inflated.
Buying New Tires
To find out what kind and size of tires you need, look at
the Certification/Tire label.
The tires installed on your vehicle when it was new had
a Tire Performance Criteria Specification (TPC Spec)
number on each tire's sidewall. When you get new tires,
get ones with that same TPC Spec number. That way
your vehicle will continue to have tires that are designed
to give proper endurance, handling, speed rating,
traction, ride and other things during normal service on
your vehicle. If your tires have an all
-season tread
design, the TPC number will be followed by an ªMSº
(for mud and snow).

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6-56
If you ever replace your tires with those not having a
TPC Spec number, make sure they are the same size,
load range, speed rating and construction type (bias,
bias
-belted or radial) as your original tires.
CAUTION:
Mixing tires could cause you to lose control while
driving. If you mix tires of different sizes or types
(radial and bias
-belted tires), the vehicle may not
handle properly, and you could have a crash.
Using tires of different sizes may also cause
damage to your vehicle. Be sure to use the same
size and type tires on all wheels.
CAUTION:
If you use bias-ply tires on your vehicle, the
wheel rim flanges could develop cracks after
many miles of driving. A tire and/or wheel could
fail suddenly, causing a crash. Use only radial
-ply
tires with the wheels on your vehicle.
Uniform Tire Quality Grading
The following information relates to the system developed
by the United States National Highway Traffic Safety
Administration, which grades tires by treadwear, traction
and temperature performance. (This applies only to
vehicles sold in the United States.) The grades are molded
on the sidewalls of most passenger car tires. The Uniform
Tire Quality Grading system does not apply to deep tread,
winter
-type snow tires, space-saver or temporary use spare
tires, tires with nominal rim diameters of 10 to 12 inches
(25 to 30 cm), or to some limited
-production tires.
While the tires available on General Motors passenger
cars and light trucks may vary with respect to these
grades, they must also conform to Federal safety
requirements and additional General Motors Tire
Performance Criteria (TPC) standards.

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6-60 Tire Chains
NOTICE:
If your vehicle has dual wheels, P265/75R16 or
LT265/75R16 size tires, don't use tire chains.
They can damage your vehicle because there's
not enough clearance.
Use another type of traction device only if its
manufacturer recommends it for use on your
vehicle and tire size combination and road
conditions. Follow that manufacturer's
instructions. To help avoid damage to your
vehicle, drive slowly, readjust or remove the
device if it's contacting your vehicle, and don't
spin your wheels.
If you do find traction devices that will fit, install
them on the rear tires.
NOTICE: (Continued)
NOTICE: (Continued)
If you don't have dual wheels or if you have a tire
size other than P265/75R16 or LT265/75R16, use
tire chains only where legal and only when you
must. Use chains that are the proper size for your
tires. Install them on the tires of the rear axle.
Don't use chains on the tires of the front axle.
Tighten them as tightly as possible with the ends
securely fastened. Drive slowly and follow the
chain manufacturer's instructions. If you can
hear the chains contacting your vehicle, stop and
retighten them. If the contact continues, slow
down until it stops. Driving too fast or spinning
the wheels with chains on will damage
your vehicle.

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6-68
GM Vehicle Care/Appearance Materials
PART NUMBERSIZEDESCRIPTIONUSAGE
99495423 in. x 25 in.Polishing Cloth ± Wax TreatedExterior polishing cloth
105017216 oz. (0.473 L)Tar and Road Oil RemoverRemoves tar, road oil and asphalt
105017316 oz. (0.473 L)Chrome Cleaner and PolishUse on chrome, stainless steel, nickel, copper and brass
105017416 oz. (0.473 L)White Sidewall Tire CleanerRemoves soil and black marks from whitewalls
105021432 oz. (0.946 L)Vinyl CleanerCleans vinyl tops, upholstery and convertible tops
105042723 oz. (0.680 L)Glass CleanerRemoves dirt, grime, smoke and fingerprints
105287016 oz. (0.473 L)Wash Wax ConcentrateCleans and lightly waxes
1052918**8 oz. (0.237 L)Armor All
ProtectantProtects leather, wood, acrylics, Plexiglas
, plastic,
rubber and vinyl
105292516 oz. (0.473 L)Multi-Purpose Interior
CleanerCleans carpets, seats, interior trim, door panels
and floor mats
105292916 oz. (0.473 L)Wheel CleanerSpray on and rinse with water
10529308 oz. (0.237 L)Capture Dry Spot RemoverAttracts, absorbs and removes soils
1234500216 oz. (0.473 L)Armor All
CleanerCleans and shines a variety of surface types
123457212.5 sq. ft.Synthetic ChamoisShines vehicle without scratching
1234572512 oz. (0.354 L)Silicone Tire ShineSpray on tire shine
1237796416 oz. (0.473 L)Finish EnhancerRemoves dust, fingerprints and surface contaminants
1237796616 oz. (0.473 L)Cleaner WaxRemoves light scratches and oxidation and protects finish
1237798416 oz. (0.473 L)Surface CleanerRemoves contaminants, blemishes and swirl marks
See your General Motors Parts Department for these products. ** Not recommended for use on instrument panel vinyl.
See ªFluids and Lubricantsº in the Index.