Chevrolet 10 Series 1968, Service Manual

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WHEELS AND TIRES 10-10
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 instruc­
tion of operators. Driving more slowly on curves and
turns will avoid grinding rubber off tires. To offset nor­
mal cornering wear as much as possible, tires should be
interchanged at regular intervals.
Wheel and Tire Balancing
It is desirable from the standpoints of tire wear and
vehicle handling ease to maintain proper balance of front
wheel and tire assemblies on all models. A ll wheels in­
tended for use on front of vehicle, such as those switched
during periodic tire rotation and those installed as new
or repaired replacement equipment should be accurately
balanced. This may be accomplished by either of the two
types of balancing systems in current 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 in­
cluded in the balancing procedure and thereby have any
existing unbalance corrected.
Truck Wheel Balance W eights
A ll 1968 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 assem­
bly 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 a chunk of
dirt on the rim will always rotate by itself until the heavy
side is at 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.
• Bent wheels that have runout over 1/16" on 1/2,
3/4 and 1 ton, or 1/8" on 1 1/2 and 2 ton trucks
should either be replaced or straightened before being
balanced.
Fig . 4 —Installation of Spacer Ring
• 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 exceed­
ing 3/16" on tire sizes through 19.5" and 5/16" on
sizes larger than 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.
WHEELS
Cast Spoke Wheels
Cast spoke wheels with demountable rims are available
oh 50 and 60 series only. Rim and tire may be removed
from the wheel after removing nuts and clamps. The
tires
may then be serviced as outlined under
“ Maintenance” .
CA U TIO N : When removing wheel, loosen all
nuts approximately flush with end of stud, then
tap clamps to loosen wheel. Do not remove nuts
until clamps are free as clamp may fly off stud.
Installation of Rims on W heels
D ual W heels
1. Before positioning inner rim, thoroughly clean all
contact surfaces on both rim and wheel.
2. After inner rim is positioned, install separator ring
as shown in Figure 4.
3
. Install outer rim and proceed as outlined under “ dual
and Single Wheels” .
D ual and Sin g le W heels
When installing the tire and rim on the wheel, the fo l­
lowing procedure should be followed:
CHEVROLET TRUCK SERVICE MANUAL