Tire Wear Inspection

Tire Wear Inspection
To maximize tire performance, inspect the tires for signs of incorrect inflation and uneven wear which may indicate a need for balancing, rotation or front suspension alignment. Tires should also be checked frequently for cuts, stone bruises, abrasions, blisters, and for objects that may have become embedded in the tread. More frequent inspections are recommended when rapid or extreme temperature changes occur or when road surfaces are rough or occasionally littered with debris.

Tire Wear Diagnosis
New tires should be installed if the wear indicators are exposed or if there is severe shoulder wear. Shoulder wear is usually caused by either excessive camber or excessive toe on radial tires.

Sometimes incorrect rear toe settings or damaged struts will cause severe cupping' or scalloped' tire wear on non-drive wheels.

Incorrect rear toe alignment will also cause other unusual wear patterns.

Road Test
A tire vibration diagnostic procedure always begins with a road test. The road test and customer interview (if available) will provide much of the information needed to find the source of a vibration.

During the road test, drive the vehicle on a road that is smooth and free of undulations. If vibration is apparent, note and record the following:
^ The speed at which the vibration occurs.
^ What type of vibration occurs in each speed range. mechanical or audible.
^ How the vibration is affected by changes in the following: engine torque. vehicle speed. engine speed.
^ Type of vibration-sensitivity: torque sensitive, vehicle speed sensitive or engine speed sensitive.

The following explanations help isolate the source of the vibration.

Torque Sensitive
This means that the condition may be improved or made worse by accelerating, decelerating, coasting, maintaining a steady vehicle speed or applying engine torque.

Vehicle Speed Sensitive
This means that the vibration always occurs at the same vehicle speed and is not affected by engine torque, engine speed or the transmission gear selected.

Engine Speed Sensitive
This means that the vibration occurs at varying vehicle speeds when a different transmission gear is selected. It may sometimes be isolated by increasing or decreasing engine speed with the transmission in NEUTRAL or by stall testing with the transmission in gear. If the condition is engine speed sensitive, the cause is probably not related to the tires.

If the road test indicates that there is tire whine, but no shake or vibration, the noise originates with the contact between the tire and the road surface.

A thumping noise usually means that the tire has a flat or soft spot making a noise as they slap the roadway. Tire whine may be distinguished from axle noise. Tire whine remains the same over a range of speeds.

Tires show excess wear on edge of treads
Possible Source(s):
^ Tires under-inflated
Action(s) to take:
^ Correct pressure to specification.
Possible Source(s):
^ Vehicle overloaded
Action(s) to take:
^ Correct as required.

Tires show excess wear on edge of treads (having the correct tire pressures).
Possible Source(s):
^ Incorrect toe setting
Action(s) to take:
^ Set to specification.

Tires show excess wear in center of tread.
Possible Source(s):
^ Tires over-inflated
Action(s) to take:
^ Correct pressure to specification.

Other excessive tire wear problems
Possible Source(s):
^ Incorrect tire pressure
Action(s) to take:
^ Correct pressure to specification.
Possible Source(s):
^ Incorrect tire / wheel usage
Action(s) to take:
^ Install correct tire and wheel combination.
Possible Source(s):
^ Loose or leaking dampers
Action(s) to take:
^ Tighten or install a new as necessary.
Possible Source(s):
^ Geometry out of alignment
Action(s) to take:
^ Check and adjust.
Possible Source(s):
^ Loose, worn or damaged suspension components
Action(s) to take:
^ Inspect, repair or install a new as necessary.
Possible Source(s):
^ Wheel and tire assembly out of balance
Action(s) to take:
^ Balance wheel and tire assembly.
Possible Source(s):
^ Excessive lateral or radial runout of wheel or tire
Action(s) to take:
^ Check, repair or install a new as necessary.

Wheel mounting is difficult
Possible Source(s):
^ Incorrect application or mismatched parts, including wheel studs and wheel nuts. Corroded, worn or damaged parts
Action(s) to take:
^ Clean or install a new part.

Wobble or shimmy affecting wheel runout
Possible Source(s):
^ Damaged wheel (eventually damaging wheel bearings and causing uneven tire wear)
Action(s) to take:
^ Inspect wheel rims for damage and runout. Install a new wheel rim as necessary.

Excessive vibration, rough steering or severe tire wear
Possible Source(s):
^ Loose or incorrect attaching parts
Action(s) to take:
^ Tighten or install new parts.

Vehicle vibrations
Possible Source(s):
^ Tires / wheels mismatched
Action(s) to take:
^ Install correct tire / wheel combination.
Possible Source(s):
^ Inflation pressure too high or low
Action(s) to take:
^ Correct pressure to specification.
Possible Source(s):
^ Uneven tire wear
Action(s) to take:
^ Refer to Diagnosis and Testing in this section.
Possible Source(s):
^ Out-of-balance wheel, tire, wheel hub or disc assembly
Action(s) to take:
^ Determine the out-of-balance component and balance or install a new part.
Possible Source(s):
^ Damaged or distorted wheel from road impact hazard or incorrect handling
Action(s) to take:
^ Install a new wheel.
Possible Source(s):
^ Excessive radial runout
Action(s) to take:
^ Install a new wheel or tire. Check for incorrect wheel and tire specifications.
Possible Source(s):
^ Excessive lateral runout
Action(s) to take:
^ Install a new wheel or tire.
Possible Source(s):
^ Incorrectly seated tire
Action(s) to take:
^ Remount the tire.
Possible Source(s):
^ Loose wheel mountings - damaged wheel studs, wheel nuts, worn or broken wheel hub face or foreign material on mounting faces
Action(s) to take:
^ Tighten or install new parts. Clean mounting surfaces.
Possible Source(s):
^ Defective wheel bearings
Action(s) to take:
^ Install a new bearing set.
Possible Source(s):
^ Brake disc imbalance
Action(s) to take:
Possible Source(s):
^ Water in tires
Action(s) to take:
^ Remove water.
Possible Source(s):
^ Loose engine or transmission mounts
Action(s) to take:
^ Tighten or install a new mount.
Possible Source(s):
^ Incorrect front end alignment
Action(s) to take:
^ Align front end.
Possible Source(s):
^ Loose or worn driveline or suspension parts
Action(s) to take:
^ Repair or install new parts.
Possible Source(s):
^ Excessive driveshaft runout or imbalance
Action(s) to take:
^ Install a new driveshaft.
Possible Source(s):
^ Worn or damaged flexible drive joint
Action(s) to take:
^ Install a new drive shaft.

Damaged wheel hub stud threads
Possible Source(s):
^ Sliding wheel across the wheel studs during installation. Loose wheel nuts
Action(s) to take:
^ Install new wheel studs.

Broken wheel studs
Possible Source(s):
^ Loose or overtightened wheel nuts
Action(s) to take:
^ Install new wheel studs.

Corrosion / contamination streaks from the wheel hub wheel stud holes
Possible Source(s):
^ Loose wheel nuts
Action(s) to take:
^ Check complete assembly. Install new parts. Follow correct torque procedure.

Wheel difficult to remove from wheel hub
Possible Source(s):
^ Corrosion
Action(s) to take:
^ Apply a small amount of grease to the wheel hub face and spigot location.

Damaged wheel nuts
Possible Source(s):
^ Loose wheel assembly
Action(s) to take:
^ Install new wheel nuts. Follow correct torque procedure.
Possible Source(s):
^ Over-tightened wheel nuts
Action(s) to take:
^ Install new wheel nuts. Follow correct torque procedure.

Frozen wheel nuts
Possible Source(s):
^ Corrosion or galling
Action(s) to take:
^ If corrosion is light, wire brush away corrosion. If corrosion is excessive install new wheel studs and wheel nuts.