Engine Speed Sensitive

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 indictors 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.
^ How the vibration is affected by changes in the following:
^ 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.