Tires: Testing and Inspection

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

Torque Sensitive
This means that the condition can 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 gear selection.

Engine Speed Sensitive
This means that the vibration occurs at varying vehicle speeds when a different gear is selected. It can 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 tires.
If the road test indicates that there is tire wine, 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 is flat or has soft spots making a noise as they slap the roadway. Tire whine can be distinguished from axle noise, as tire whine remains the same over a range of speeds.

Symptom Chart
Condition(s):
Uneven tire wear.

Possible Source(s):
^ Incorrect tire inflation.

Action(s) to take:
^ Correct to specification.

Possible Source(s):
^ Excessive radial and lateral runout.

Action(s) to take:
^ Renew tire or wheel.

Possible Source(s):
^ Out of specification steering geometry.

Action(s) to take:
^ Realign steering geometry.

Possible Source(s):
^ Worn ball joint.

Action(s) to take:
^ Renew damaged component, realign steering geometry.

Possible Source(s):
^ Worn tie-rod end.

Action(s) to take:
^ Renew component, realign steering geometry.

Possible Source(s):
^ Incorrect tire/wheel usage.

Action(s) to take:
^ Install correct tire and wheel combination.

Possible Source(s):
^ Loose or leaking shock absorbers.

Action(s) to take:
^ Tighten or Renew as necessary.

Possible Source(s):
^ Suspension 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 Renew 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 Renew as required.

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 to specification.

Tires show excess wear on edge of treads (with tire pressures correct).

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

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:
^ Follow the manufacturer's specifications. Clean or Renew.

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. Renew as required.

Vehicle vibrations from wheels and tires.

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.

Possible Source(s):
^ Wheel and tire assembly imbalance.

Action(s) to take:
^ Balance wheel and tire assembly.

Possible Source(s):
^ Brake disc imbalance.

Action(s) to take:
^ Check brake disc cooling fins for mud and foreign material.
^ Check for damage or disc heavy spot.

Possible Source(s):
^ Damaged or distorted wheel.

Action(s) to take:
^ Renew wheel.

Possible Source(s):
^ Excessive radial run-out of wheel or tire.
^ Excessive lateral run-out of wheel or tire.

Action(s) to take:
^ Renew 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 Renew worn or damaged parts. Clean mounting surfaces.

Possible Source(s):
^ Defective wheel bearings.

Action(s) to take:
^ Renew worn or damaged bearing sets.

Possible Source(s):
^ Water in tires.

Action(s) to take:
^ Remove water.

Damaged wheel stud threads.

Possible Source(s):
^ Sliding wheel across the wheel studs during installation.
^ Loose wheel nuts.

Action(s) to take:
^ Renew wheel studs.

Broken wheel studs.

Possible Source(s):
^ Loose or overtightened wheel nuts.

Action(s) to take:
^ Renew wheel studs.

Corrosion/contamination streaks from wheel stud holes.

Possible Source(s):
^ Loose wheel nuts.

Action(s) to take:
^ Check complete assembly. Renew damaged parts. Apply correct torque setting.

Damaged wheel nuts.

Possible Source(s):
^ Loose wheel assembly.
^ Over-tightened wheel nuts.

Action(s) to take:
^ Renew wheel nuts. Apply correct torque setting.

Seized wheel nuts.

Possible Source(s):
^ Corrosion

Action(s) to take:

^ CAUTION: Do not permit lubricant to contaminate wheel hub stud holes or wheel nut seats.

If corrosion is light, wire brush away corrosion. If corrosion is excessive renew wheel studs and wheel nuts. Lubricate the first three threads of wheel studs with a graphite based lubricant.