DIAGNOSIS AND TESTING
TIRE NOISE AND 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 a noise or vibration,
drive the vehicle over a smooth road at varying
speeds. Note the noise level during acceleration and
deceleration. Engine, differential and exhaust noises
will change as speed varies, while tire noise will usu-
ally remain constant.
Unusual tire noise can be associated with tire and
wheel vibration. For vibration, (Refer to 22 - TIRES/
WHEELS - DIAGNOSIS AND TESTING), (Refer to
22 - TIRES/WHEELS - STANDARD PROCEDURE).
For irregular tire wear, (Refer to 22 - TIRES/
WHEELS/TIRES - DIAGNOSIS AND TESTING).
TIRE TREAD WEAR INDICATORS
Tread wear indicators are molded into the bottom
of the tread grooves. When tread depth is at 1.6 mm
(1/16 in.), the tread wear indicators will appear as a
13 mm (1/2 in.) band across the tread groove in the
tire.
Tire replacement is necessary when wear indica-
tors appear in two or more tread grooves or if local-
ized balding occurs (Fig. 21).
TIRE TREAD WEAR PATTERNS
Abnormal tire tread wear can be caused by:
• Incorrect inflation pressure
• Tire/wheel unbalance
• Worn suspension components
• Improper brake operation
• Bent wheels
• Incorrect front wheel alignment
• Excessive speed when turning the vehicle
In most situations, inspection of the tire tread
wear will reveal the cause of the abnormal wear. The
illustration below (Fig. 22) shows the various types of
tire tread wear patterns and the recommended cor-
rective action.
Fig. 22 Abnormal Tire Tread Wear Patterns
Fig. 21 Tread Wear Indicators
1 - TREAD ACCEPTABLE
2 - TREAD UNACCEPTABLE
3 - WEAR INDICATOR
ZB TIRES/WHEELS 22 - 13
TIRES (Continued)
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