Chevrolet 1980 Light Duty Truck Service Manual page 309

, the transfer of weight may also overload the
Second
outside tires so much that they are laterally distorted
resulting in excessive wear on the outside half of the tire,
producing a type of wear like that caused by excessive
positive camber.
Cornering wear can be most easily distinguished from
abnormal camber wear by the rounding of the outside
shoulder or edge of the tire and by the roughening of the
tread surface which denotes abrasion.
Cornering wear often produces a fin or raised portion
along the inside edge of each row in the tread pattern. In
some cases this fin is almost as pronounced as a toe-in fin,
and in others, it tapers into a row of tread blocks to such
an extent that the tire has a definite "step wear" appearance.
The only remedy for cornering wear is proper
instruction of operators. Driving more slowly on curves and
turns will avoid grinding rubber off tires. To offset normal
cornering wear as much as possible tires should be
interchanged at regular intervals.
W heel and Tire Balancing
It is desirable from the standpoints of tire wear and
vehicle ride and handling ease to maintain proper balance
of wheel and tire assemblies on all models. This may be
accomplished by either of the two types of balancing
systems in currect use which balance wheels either on the
vehicle or off. The "on the vehicle" type, however, is the
more desirable in that all rolling components (brake drums,
bearings, seals, etc.) are included in the balancing procedure
and thereby have any existing unbalance corrected.
Truck W heel Balance W eights
All truck wheels equipped with a tubular side ring
(rolled flange rim) on the outboard side of the wheel rims
require special design weights to fit. Dynamic balancing can
be accomplished through use of these special balance
weights which are designed only for installations on the
outboard side of these wheels. Conventional weights fit only
the inboard side of these wheels.
Static Balance
Static balance (sometimes called still balance) is the
equal distribution of weight of the wheel and tire assembly
about the axis of rotation in such a manner that the
assembly has no tendency to rotate by itself, regardless of
its position. For example: A wheel with chunk of dirt on
the rim will always rotate by itself until the heavy side is
a the bottom. Any wheel with a heavy side like this is
statically out of balance. Static unbalance of a wheel causes
a hopping or pounding action (up and down) which
frequently leads to wheel "flutter" and quite often to wheel
"tramp".
Dynamic Balance
Dynamic balance (sometimes called running balance
means that the wheel must be in static balance, and also run
smoothly at all speeds.
To insure successful, accurate balancing, the following
precautions must be observed:
• Wheel and tire must be clean and free from all foreign
matter.
• The tires should be in good condition and properly
mounted with the balance mark on the tire, if any, lined up
with the valve.
WHEELS AND TIRES
Fig. 3E-10~Wheel Nut Tightening Sequence
• Bent wheels that have runout over 1/16" should be
replaced.
• Inspect tire and wheel assembly to determine if an
eccentric or out-of-round condition exists. Note that this
condition, if severe, cannot be "balanced out". An assembly
which has an out-of-round condition exceeding 3/16" on
tire sizes through 19.5" is not suitable for use on the front
of the vehicle. Its use on the rear should be governed by its
general condition and whether the roundness defect
seriously detracts from overall ride quality.
• When balancing wheels and tires, it is recommended
that the instructions covering the operation of the wheel
balancer being used be closely followed.
• When balancing truck type nylon tires, tires must be
hot (run for several miles) before raising vehicle to balance
so that flat spot is elimated. A tire which is flat spotted will
be incorrectly balanced.
WHEEL INSTALLATIO N
Single W heels
When installing the tire and wheel on the vehicle, the
following procedure should be followed:
After wheel nuts are put on loosely, turn the wheel
until one nut is at the top of the bolt circle; tighten the nut
just snug. Snug up the remaining nuts criss-cross to
minimize runout, then tighten the nuts to the recommended
torque alternately and evenly to avoid excessive runout.
CAUTIO N: Before re-installing aluminum
wheels, any build up of corrosion of the
wheel mounting surface and brake druni
or disc mounting
removed by scraping and w ire brushing.
Installation of aluminum w heels w ithout
good metal-to-metal
mounting surfaces can result in loosening
of the wheel nuts w hich can eventually
allow the wheel to come off w hile the
vehicle is in motion, causing loss of
control.
3E-7
surface should be
contact at the
L IG H T TRU CK S ER V IC E M AN UAL