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WHEELS A N D TIRES 10-5
WHEELS
The wheel and tire assembly should be removed from
vehicles equipped with disc brakes to properly perform
balancing operations. This is necessary due to drag of
the spring loaded brake shoes on the disc.
Static Balancing (W/Tire)
Static Balance (still balance) is the equal distribution
of weight of the wheel and tire assembly about the axis
of rotation so that the assembly has no tendency to rotate
by itself. Static unbalance causes the pounding action of
the front wheels that is called "tramp".
To correct static unbalance (front and rear): The
quickest and best methods to correct static unbalance
are through the use of wheel balancers which are com-
mercially available. Refer to the Information and in-
structions included with these balaricers.
Dynamic Balancing (W/Tire)
Dynamic Balance (running balance) requires the wheel
to be not only in static balance, but balanced and running
smoothly while turning on an axis which runs through the
centerline of the wheel and tire perpendicular to the axis
of rotation.
The quickest and best methods of testing and correcting
dynamic unbalance are by the use of dynamic wheel
balancers which are commercially available. These bal-
ancers include all necessary information on where and
how the balancing weights should be placed. The follow-
ing information, however, will help in the correction of
dynamic balance.
NOTE:
Before
attempting
to balance the
wheels, check to be certain that no foreign
matter has been trapped in the wheel ventila-
tion slots or in the accessory wheel discs. This
is especially important if the vehicle has been
run in soft mud and then parked in freezing
weather.
When a wheel that is statically unbalanced is dynam-
ically in balance the dynamic balance can be retained
while correcting "the static balance by installing the cor-
rective weights so that half of the weight required is
placed on the inner edge of the rim and the other half
on the outer edge of the rim.
Dynamic unbalance can be corrected without destroying
static balance by installing weights so half of weight
required for dynamic balance is placed on the rim op-
posite the heavy point, while the other half is placed 180°
away and on the opposite side of the rim.
NOTE:
Vehicles with wire wheel covers should
have the wheels balanced with the wire wheel
covers installed on the wheels.
Run Out (W/OTire)
The wheels should not run out (wobble) more than
1/16" as measured on the side of the rim at the base
of the tire. Excessive run-out is the result of a bent
wheel, an improperly mounted wheel, worn knuckle bear-
ings or steering connections. These parts should be
checked for correct adjustment, proper alignment and
wear whenever excessive run-out is encountered.
The wheels should also run concentric with the steering
knuckle spindle within 1/16 inch as measured on the tire
bead seat of the rim with the tire removed.
Wheel run-out, eccentricity and balance are closely
associated with steering and front wheel alignment.
Further information on these subjects will be found under
"Suspension".
Cleaning Aluminum Wheels
Do not use wire brush or abrasive cleaners when
cleaning wheels. Use only cleaners that will not react
with aluminum.
SERVICE OPERATIONS
TIRES
Removal
Dismounting tubeless tires presents no problems if the
correct procedures are used and the following precau-
tions observed.
1. Remove the valve cap and valve core. Let out all the
air.
2. Press the inner side of the tire into the rim well.
Use bead loosening tool or if regular tire irons are
used, take particular care not to injure or tear the
sealing ribs on the bead.
CAUTION:
Never use tire irons with sharp
edges or corners.
3. Using tire irons on the opposite side, remove bead,
taking small "bites" around the rim.
4. Turn the tire over, and use two tire irons, one be-
tween the rim flange and the bead to pry the rim
upward, the other iron to pry outward between the
bead seat and the bead.
Installation
Extreme care must be exercised to prevent injury to
the sealing bead and circumferential bead when forcing
tire over rim.
1. Apply a light film of Ruglyde or other suitable rubber
lubricant to sealing bead of tire.
NOTE:
The use of excessive lubrication may
lead to rim slippage and subsequent breaking of
air seal.
2. Carefully mount the outer bead in usual manner by
using tire irons, taking small "bites" around rim,
being careful not to injure the tire bead.
CAUTION:
DO NOT use a hammer, as damage
to the bead will result.
3. Install the inner bead in the same manner.
NOTE:
If a seal cannot be effected in the fore-
going manner with the rush of air it can be
,
accomplished by applying to the circumference
of the tire a tire mounting band or heavy sash
cord and tightening with the use of a tire iron.
On tire mounting machines, bouncing the tire
assembly is not required. The tire should be
CHEVROLET CHASSIS SERVICE MANUAL
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