TIRE NOISE OR VIBRATION
Radial-ply tires are sensitive to force impulses
caused
by
improper
mounting,
vibration,
wheel
defects, or possibly tire imbalance.
To find out if tires are causing the noise or vibra-
tion, drive the vehicle over a smooth road at varying
speeds. Note the noise level during acceleration and
deceleration. The engine, differential and exhaust
noises will change as speed varies, while the tire
noise will usually remain constant.
SERVICE PROCEDURES
ROTATION
Tires on the front and rear operate at different
loads and perform different steering, driving, and
braking functions. For these reasons they wear at
unequal rates and tend to develop irregular wear
patterns. These effects can be reduced by rotating
the tires at regular intervals. The benefits of tire
rotation are:
• Increase tread life
• Maintain traction levels
• A smooth, quiet ride
The suggested method of tire rotation is (Fig. 6).
Other rotation methods can be used, but they will
not provide all the tire longevity benefits.
MATCH MOUNTING
Wheels and tires are match mounted at the factory.
This means that the high spot of the tire is matched
to the low spot on the wheel rim. Each are marked
with a bright colored temporary label on the out-
board surface for alignment. The wheel is also
marked permanently on the inside of the rim in the
tire well. This permanent mark may be a paint dot
or line, a permanent label or a stamped impression
such as an X. An optional location mark is a small
spherical indentation on the vertical face of the out-
board flange on some non styled base steel wheels.
The tire must be removed to locate the permanent
mark on the inside of the wheel.
Before dismounting a tire from its wheel, a refer-
ence mark should be placed on the tire at the valve
Fig. 4 Tread Wear Indicators
1 – TREAD ACCEPTABLE
2 – TREAD UNACCEPTABLE
3 – WEAR INDICATOR
Fig. 5 Tire Wear Patterns
22 - 4
TIRES AND WHEELS
DN
DIAGNOSIS AND TESTING (Continued)