The vehicle alignment experts at Josam Products. Inc. have compiled the following list of tire wear symptoms and their probable causes.

• Shoulder step/chamfer wear. Even tread wear with a small step or chamfer worn off the outer edge of cither shoulder rib. Cause: This is typical radial tire wear and normally should not adversely affect the service life of the tire.

• Cupping or scalloping. Cause: Severe out of balance. Improper fitting of the tire or rim.

• Brake skid flat spotting. Cause: Often seen on trailer tires. New. faulty or just badly balanced braking systems. Driver abuse.

• Diagonal flat spots. These may be repeated evenly around the tread surface. Cause: Run out of spider rims: out of balance; loose wheel bearings: mismatched diameters of inflation pressure of dual tires. Will be exaggerated by any tracking error.

• Eccentric/out-of-round wear. Tread depth varies around the tire. Cause: Out-of-round or out-of-balance tires. rims or brake drums. Poor tire fitting.

• Good wear pattern, but fast rate of wear. Cause: Severe operating conditions. High speeds, loads or horsepower.

• Accelerated wear on both edges of a tire. Cause: Under-inflation.

• Accelerated wear on the center of a tire. Cause: Over-inflation.

• Heel and toe wear. Cause: Typical or lug type or block type tread patterns. Will be exaggerated by camber error, mismatched diameters of inflation pressure and trading error. This symptom normally u ill not affect overall service life of the tire.

• Feathering. Cause: Trading error.

• Accelerated wear on one edge of a tire with no feathering. Cause: Camber error.

• Both tires on one axle feathering from outside to inside and showing accelerated wear on the leading (outer) edges. Cause: Toe-in error.

• Both tires on one axle, especially a steering axle, feathering from left to right or right to left and showing accelerated wear on the leading edges. Cause: Out-of-square or out-of-parallel tracking error. The error may or may not occur on the axle that shows the wear and in the case of steering axles the error is most likely to be in the drive axle(s)

• One tire or an axle feathering and showing accelerated wear on the leading edge while the other tire wears normally. Cause: A combination of toe-in/out-of-tracking error and out-of-square or out-of-parallel trading error.

• Any tire with feathering but showing accelerated wear on the trailing edge. Cause: A combination of major camber error on this wheel and a tracking error either on this axle or another axle.

The tire experts at Goodyear Tire & Rubber Co. have put together a short checklist to help fleets ensure better tire wear:

• Use tires designed for your application.

• Make sure duals match.

• Do weekly inflation checks as a minimum.

• Maintain proper alignment settings (front end and axle parallelism) on loaded vehicles.

• Rotate unevenly worn tires with 50 percent of tread depth remaining to equalize wear.

• Keep educating your drivers about good driving habits.

The Goodyear Tire & Rubber Company suggests five tips for maintaining proper tire inflation pressure.

1. Inflate for the maximum load the tire must carry.

2. Check inflation pressure when tires are cold.

3. Avoid introducing moisture into tire by using air dryers in the system.

4. Use flow-through metal valve caps.

5. Use tire safety cage.

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