General Testing

PRESSURE GAUGES
A quality air pressure gauge is recommended to check tire pressure. After checking the air pressure, replace valve cap finger tight.

Fig. 2:

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 inch), the tread wear indicators will appear as a 13 mm (1/2 inch) band across the tread groove in the tire. Tire replacement is necessary when wear indicators appear in two or more tread grooves or if localized balding occurs.





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 shows the various types of tire tread wear patterns and the recommended corrective action.

Rapid wear from the tire tread shoulders is usually caused by under-inflation. If this type of wear occurs and the tires are serviceable, inflate the tires to their recommended cold inflation pressure.

Rapid wear from the center of tire tread is usually caused by over-inflation. If this type of wear occurs and the tires are serviceable, inflate them with the recommended air inflation pressure when they are cold.

Cracked treads are usually caused by under-inflation or excessive high-speed vehicle operation. Tires with cracked treads should be replaced and the replacement tires should be properly maintained to avoid a recurrence of the failure.

Excessive wear from one tread shoulder can be caused by excessive speed on turns or by an incorrect camber angle. An incorrect negative camber angle will cause excessive wear from the tire inside shoulder. An incorrect positive camber angle will cause excessive wear from the tire outside shoulder. If this type of tread wear occurs, measure the camber angle. If the camber angle is within the specified limits, caution the owner about excessive speed when turning.

An incorrect wheel toe position will cause the tire tread surface to develop a feathered edge. One side of the tread will be rounded while the opposite side will have a feathered edge. This type of tread wear indicates that the tire is side slipping and scuffing as it moves over the street/road surface.

A feathered tread edge that faces toward the vehicle indicates an excessive wheel toe-in position. A feathered tread edge that faces away from the vehicle indicates an excessive wheel toe-out position. The direction that a feathered edge has developed can be determined by moving the tips of your fingers over the tire tread surface. Bent steering components can also cause this type of tire tread wear.

If a feathered edge develops on the tread of a tire(s), measure and correct the wheel toe position as necessary.

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 the noise or vibration, drive the vehicle over a smooth road at varying speeds. Note the effect of acceleration and deceleration on noise level. Differential and exhaust noises will change in intensity as speed varies, while tire noise will usually remain constant.