1999 CHEVROLET CORVETTE Owners Manual

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6-47
CAUTION:
Mixing tires could cause you to lose control while
driving. If you mix tires of different sizes (other
than those originally installed on your vehicle) or
types (radial and bias
-belted tires), the vehicle
may not handle properly, and you could have a
crash. Using tires of different sizes (other than
those originally installed on your vehicle) may
also cause damage to your vehicle. Be sure to use
the correct size and type tires on all four wheels.
If you feel that winter tires are needed, see ªExtended
Mobility Tiresº in the Index.
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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6-48
Treadwear
The treadwear grade is a comparative rating based on
the wear rate of the tire when tested under controlled
conditions on a specified government test course. For
example, a tire graded 150 would wear one and a half
(1 1/2) times as well on the government course as a tire
graded 100. The relative performance of tires depends
upon the actual conditions of their use, however, and
may depart significantly from the norm due to variations
in driving habits, service practices and differences in
road characteristics and climate.
Traction
-- AA, A, B, C
The traction grades, from highest to lowest, are AA, A,
B, and C. Those grades represent the tire's ability to stop
on wet pavement as measured under controlled
conditions on specified government test surfaces of
asphalt and concrete. A tire marked C may have poor
traction performance. Warning: The traction grade
assigned to this tire is based on straight
-ahead braking
traction tests, and does not include acceleration,
cornering, hydroplaning, or peak traction characteristics.Temperature
-- A, B, C
The temperature grades are A (the highest), B, and C,
representing the tire's resistance to the generation of
heat and its ability to dissipate heat when tested under
controlled conditions on a specified indoor laboratory
test wheel. Sustained high temperature can cause the
material of the tire to degenerate and reduce tire life, and
excessive temperature can lead to sudden tire failure.
The grade C corresponds to a level of performance
which all passenger car tires must meet under the
Federal Motor Vehicle Safety Standard No. 109.
Grades B and A represent higher levels of performance
on the laboratory test wheel than the minimum required
by law.
Warning: The temperature grade for this tire is
established for a tire that is properly inflated and not
overloaded. Excessive speed, underinflation, or
excessive loading, either separately or in combination,
can cause heat buildup and possible tire failure.

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6-49 Wheel Alignment and Tire Balance
The wheels on your vehicle were aligned and balanced
carefully at the factory to give you the longest tire life
and best overall performance.
Scheduled wheel alignment and wheel balancing are not
needed. However, if you notice unusual tire wear or
your vehicle pulling one way or the other, the alignment
may need to be reset. If you notice your vehicle
vibrating when driving on a smooth road, your wheels
may need to be rebalanced.
Wheel Replacement
Replace any wheel that is bent, cracked, or badly rusted
or corroded. If wheel nuts keep coming loose, the wheel,
wheel bolts and wheel nuts should be replaced. If the
wheel leaks air, replace it (except some aluminum
wheels, which can sometimes be repaired). See your
dealer if any of these conditions exist.
Your dealer will know the kind of wheel you need.
Each new wheel should have the same load
-carrying
capacity, diameter, width, offset and be mounted the
same way as the one it replaces.If you need to replace any of your wheels, wheel bolts
or wheel nuts, replace them only with new GM original
equipment parts. This way, you will be sure to have the
right wheel, wheel bolts and wheel nuts for your vehicle.
CAUTION:
Using the wrong replacement wheels, wheel bolts
or wheel nuts on your vehicle can be dangerous. It
could affect the braking and handling of your
vehicle, make your tires lose air and make you lose
control. You could have a collision in which you or
others could be injured. Always use the correct
wheel, wheel bolts and wheel nuts for replacement.
NOTICE:
The wrong wheel can also cause problems with
bearing life, brake cooling, speedometer or
odometer calibration, headlamp aim, bumper
height, vehicle ground clearance and tire
clearance to the body and chassis.

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6-50
CAUTION:
Rust or dirt on the wheel, or on the parts to
which it is fastened, can make the 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 the places
where the wheel attaches to the vehicle. In an
emergency, you can use a cloth or 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.
CAUTION:
Never use oil or grease on studs or nuts. If you
do, the nuts might come loose. Your wheel could
fall off, causing a serious accident.
CAUTION:
Incorrect wheel nuts or improperly tightened
wheel nuts can cause the wheel to become loose
and even come off. This could lead to an accident.
Be sure to use the correct wheel nuts. If you have
to replace them, be sure to get new GM original
equipment wheel nuts.
NOTICE:
Improperly tightened wheel nuts can lead to
brake pulsation and rotor damage. To avoid
expensive brake repairs, evenly tighten the wheel
nuts in the proper sequence and to the proper
torque specification.

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6-51
Used Replacement Wheels
CAUTION:
Putting a used wheel on your vehicle is
dangerous. You can't know how it's been used or
how far it's been driven. It could fail suddenly
and cause an accident. If you have to replace a
wheel, use a new GM original equipment wheel.
Using the Wheel Lock Key
If you have a hardtop, the wheel lock key sits in a small
depression in the trunk rail, on the left-hand side,
underneath the carpeting.
If you have a coupe or a convertible, the wheel lock key
sits in a small depression in the trunk rail directly under
the left
-hand rear compartment cover.
Your vehicle's wheel lock key has a unique registration
number. The registration number is printed on a card
included in your lock nut package. Also on this card is
lost key replacement information. This number is not
recorded by GM or your dealer, so be sure not to lose
this card. You will need the information if you ever lose
your wheel lock key.If you or someone else is going to remove the wheels on
your vehicle, make sure that the special wheel nut socket
and wheel lock key are being used.
NOTICE:
Your wheels could be damaged if the wheel nut
socket is not used to remove your vehicle's wheels.
The wheel nut socket can be used with an air wrench or
a torque wrench. The wheel lock key can be used with a
torque wrench, but not with an air or impact wrench.
NOTICE:
Your wheel lock key or lock nuts could be
damaged if an air or impact wrench is used with
this key.

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6-52 Tire Chains
NOTICE:
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.
Lifting Your Corvette
CAUTION:
Lifting a vehicle can cause an injury. The vehicle
can slip off the jack and roll over you or other
people. You and they could be badly injured.
Find a level place to lift your vehicle. To help
prevent the vehicle from moving:
1. Set the parking brake firmly.
2. Put an automatic transmission shift
lever in PARK (P), or shift a manual
transmission to FIRST (1) or
REVERSE (R).
3. Turn off the engine.
To be even more certain the vehicle won't move,
you can put blocks in front of and behind
the wheels.

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6-53
CAUTION:
Getting under a vehicle when it is jacked up is
dangerous. If the vehicle slips off the jack, you
could be badly injured or killed. Never get under
a vehicle when it is supported only by a jack.
CAUTION:
Raising your vehicle with the jack improperly
positioned can damage the vehicle and even make
the vehicle fall. To help avoid personal injury and
vehicle damage, be sure to place the jack in the
proper location before raising the vehicle.
If you ever use a jack to lift your Corvette, such as to
display it at a show, follow the instructions that came
with the jack, and be sure to use the correct lifting points
to avoid damaging your vehicle.
NOTICE:
Lifting your vehicle improperly can damage your
vehicle and result in costly repairs not covered by
your warranty. To lift your vehicle properly,
follow the advice in this part.
To help prevent vehicle damage:

Be sure to place a block or pad between the
jack and the vehicle.

Make sure the jack you're using spans at
least two crossmember ribs.

Lift only in the areas shown in the
following pictures.
For additional information, see your dealer and
the Chevrolet Corvette service manual.

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6-54 Lifting From the Front
The front lifting point can be accessed from either the
driver's or passenger's side of the vehicle, behind the
front tires.
1. Locate the lifting point (B) on either side of your
vehicle to jack the vehicle according to the
illustration shown.
2. Be sure to place a block or pad between the jack and
the vehicle.
3. Lift the vehicle with the jack, making sure the jack
spans at least two of the crossmember ribs (A).