Hummer H1 Service Manual page 401

6-18 Wheels and Tires/Central Tire Inflation System (CTIS)
WHEEL AND TIRE BALANCING
General
There are two types of tire and wheel balancing: static and dy-
namic. Static balance is the equal distribution of weight around
the wheel circumference. Wheels that are statically unbalanced
cause a bouncing action called vehicle shake and possible
steering nibble or oscillation. This condition will eventually
cause uneven tire wear (Figure 6-28).
STEERING WHEEL NIBBLE
HEAVY SPOT
Figure 6-28: Static Imbalance Correction
Dynamic balance is the equal distribution of weight on each
side of the centerline, so that when the wheel spins there is no
tendency for it to move from side to side. Wheels that are dy-
namically unbalanced may cause wheel shimmy, vehicle shake
or a steering wheel vibration called nibble or oscillation
(Figure 6-29).
STEERING WHEEL NIBBLE
HEAVY SPOT
Figure 6-29: Static Imbalance Correction
ADD BALANCE
WEIGHTS HERE
ADD BALANCE
WEIGHTS HERE
NOTE: Most electronic off-vehicle balancers are more accu-
rate than on-vehicle spin balancers. They are easy to use and
give a dynamic (two-plane) balance. On-vehicle balancing is
not recommended. When balancing off-vehicle, the wheel
should be mounted to the balancer with a cone through the
back side of the center pilot hole or by the wheel (spindle) stud
holes. The spindle stud method is recommended for CTIS
wheels.
Balancing
1. Remove wheel and tire assembly from the vehicle.
WARNING: Remove all stones and foreign material
from the tire tread before spin balancing. Failure to fol-
low this warning may result in injury.
NOTE: Deposits of foreign material must be cleaned from the
inside of the wheel and the tire tread to obtain a good balance.
The tire should be inspected for obvious damage, then bal-
anced according to the equipment manufacturers recommenda-
tions.
2. Mount wheel and tire assembly, curb side out, on dynamic
balancer and start balance cycle (Figure 6-30).
DYNAMIC BALANCER
Figure 6-30: Dynamic Balancer Mounting
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WHEEL AND
TIRE ASSEMBLY
CURB SIDE
®