RADIAL FORCE VARIATION
Radial Force Variation can be checked using the
Hunter GSP 9700 Vibration Control System (Wheel
Balancer) or equivalent, if available. This type of
equipment helps to correct ride disturbances by
reducing the radial force variation of an assembly
through re-indexing of the tire to wheel.
The equipment manufacturer or DaimlerChrysler
Corporation may supply reference values as guide-
lines. Radial force measurements above the reference
value may not always result in a ride disturbance,
nor do they automatically mean the assembly compo-
nents are out of specification. Do not replace compo-
nents based on radial force values alone. Balancing,
runout diagnosis, re-indexing, and subjective road
testing must be performed as outlined in previous
sections of this diagnosis and testing procedure.
Use the Radial Force equipment to identify suspect
assemblies and minimize the radial forces. After all
suspect assemblies are optimized, reinstall the
assemblies and road test the vehicle. If a disturbance
still exists and all other vibration diagnostic proce-
dures have been completed, replace one tire or one
wheel at a time, starting with the assembly having
the highest force variation. Be sure to minimize each
new assembly. Road test the vehicle following each
replacement. Continue this process until the distur-
bance is resolved.
NOTE: When using Radial Force equipment, it is
critically important to set proper tire inflation pres-
sure and ensure centering of the wheel on the
equipment spindle.
RADIAL FORCE VARIATION REFERENCE
VALUES
DESCRIPTION SPECIFICATION
Total Radial Force
Variation (RFV)Less Than 22 Lbs. 2
Lbs.
Radial First Harmonic
(R1H)Less Than 16 Lbs. 2
Lbs.
Radial Second Harmonic
(R2H)Less Than 12 Lbs. 2
Lbs.
STANDARD PROCEDURE
STANDARD PROCEDURE - TIRE AND WHEEL
BALANCE
NOTE: Balance equipment must be calibrated and
maintained per equipment manufacturer's specifica-
tions.
Wheel balancing can be accomplished with either
on-vehicle or off-vehicle equipment.
NOTE: If using on-vehicle balancing equipment, on
the driving axle, remove the opposite wheel and tire
assembly.
It is recommended that a two-plane dynamic bal-
ancer be used when a wheel and tire assembly
requires balancing. A static balancer should only be
used when a two-plane balancer is not available.
Balance wheel and tire assemblies dynamically and
statically to less than 0.25 (
1¤4) ounce.
For static balancing, find location of heavy spot
causing imbalance. Counter balance wheel directly
opposite the heavy spot. Determine weight required
to counterbalance the area of imbalance. Place half of
this weight on theinnerrim flange and the other
half on theouterrim flange (Fig. 8).
For dynamic balancing, the balance equipment is
designed to indicate the location and amount of
weight to be applied to both the inner and outer rim
flanges (Fig. 9).
The aluminum wheels on this vehicle use a unique
wheel weight (Fig. 10). This wheel weight is designed
to fit the contoured surface of the wheel (Fig. 10).
When balancing an aluminum wheel, this wheel
weight must be used. Do not use any other type of
wheel weight. It will not properly fit the contour of
the wheel.
Always verify the Balance. When using off-vehicle
equipment, rotate assembly 180 degrees on balance
equipment to verify balance. Variation should not be
more than 0.125 (
1¤8) ounce. If variation is more than
0.125 ounce, balancing equipment could be malfunc-
tioning.
RSTIRES/WHEELS22-5
TIRES/WHEELS (Continued)
DIAGNOSIS AND TESTING - TIRE WEAR
PATTERNS
Under inflation will cause wear on the shoulders of
tire. Over inflation will cause wear at the center of
tire.
Excessive camber causes the tire to run at an
angle to the road. One side of tread is then worn
more than the other (Fig. 22).
Excessive toe-in or toe-out causes wear on the
tread edges and a feathered effect across the tread
(Fig. 22).
DIAGNOSIS AND TESTING - TREAD WEAR
INDICATORS
Tread wear indicators are molded into the bottom
of the tread grooves. When tread depth is 1.6 mm
(1/16 in.), the tread wear indicators will appear as a
13 mm (1/2 in.) band (Fig. 23).
Tire replacement is necessary when indicators
appear in two or more grooves or if localized balding
occurs.
STANDARD PROCEDURE
STANDARD PROCEDURE - TIRE INFLATION
PRESSURES
The specified tire pressures have been chosen to
provide safe operation, vehicle stability, and a smooth
ride. The proper tire pressure specification can be
found on the Tire Inflation Pressure Label provided
with the vehicle (usually on the driver's side B-pil-
lar).A quality air pressure gauge is recommended to
check tire air pressure. Tire pressure should be
checked cold once per month. Check tire pressure
more frequently when the weather temperature var-
ies widely. Tire pressure will decrease when the out-
door temperature drops. After checking the air
pressure, replace valve cap finger tight.
Fig. 22 Tire Wear Patterns
Fig. 23 Tread Wear Indicators
1 - TREAD ACCEPTABLE
2 - TREAD UNACCEPTABLE
3 - WEAR INDICATOR
22 - 16 TIRES/WHEELSRS
TIRES (Continued)
