| Diagnosis and Testing Inspection and Verification Visual Inspection Chart | Mechanical | | Wheel(s) | | Tire(s) | | Tire pressure(s) * | | Wheel nuts | | Wheel studs | | * Vehicles equipped with a tire pressure monitoring system must be inspected for correct operation using the diagnostic tool. | To maximize tire performance, inspect the tires for signs of incorrect inflation and uneven wear which may indicate a need for balancing, rotation or 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 foreign material. As a further visible check of tire condition, tread wear indicators are molded into the bottom of the tread grooves. When these indicator bands become visible, new tires must be installed. Tire Wear Diagnosis Uneven wear is usually caused by either excessive camber or excessive toe on tires. Sometimes incorrect toe settings or worn struts will cause severe `cupping' or `scalloped' tire wear on non-driven wheels. Severely incorrect toe settings will also cause other unusual wear patterns. Tire Vibration Diagnosis 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:
- vehicle speed sensitive The following explanations help isolate the source of the 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 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 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 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 is flat or has soft spots making a noise as they slap the roadway. Tire whine can be distinguished from axle noise. Tire whine remains the same over a range of speeds. A complete road test procedure is described in Section 100-04. REFER to: Noise, Vibration and Harshness (NVH) (100-04 Noise, Vibration and Harshness, Diagnosis and Testing). Symptom Chart | Symptom | Possible Sources | Action | | Tire(s) show excess wear on edge of tread | * Tire(s) under-inflated. | * ADJUST the tire pressure(s). | | * Vehicle overloaded. | * CORRECT as necessary. | | * Incorrect wheel alignment. | * ADJUST the wheel alignment. REFER to: (204-00 Suspension System - General Information) Specifications (Specifications), Front Toe Adjustment (General Procedures). | | Tire(s) show excess wear in center of tread | * Tire(s) over-inflated. | * ADJUST the tire pressure(s). | | Other excessive tire wear concerns | * Incorrect tire pressure(s). | * ADJUST the tire pressure(s). | | * Wheel and tire assemblies need rotating. | * ROTATE the wheel and tire assemblies. | | * Incorrect wheel alignment. | * ADJUST the wheel alignment. REFER to: (204-00 Suspension System - General Information) Specifications (Specifications), Front Toe Adjustment (General Procedures). | | * Vehicle overloaded. | * CORRECT as necessary. | | * Loose or leaking front strut and spring assembly. | * TIGHTEN or INSTALL new suspension components as necessary. REFER to: Shock Absorber and Spring Assembly (204-01 Front Suspension, Removal and Installation). | | * Wheel bearings worn. | * INSTALL new wheel bearings as necessary. REFER to: Front Wheel Bearing (204-01 Front Suspension, Removal and Installation), Rear Wheel Bearing (204-02 Rear Suspension, Removal and Installation). | | * Suspension components, bushings and ball joints. | * CHECK or INSTALL new suspension components as necessary. | | * Excessive lateral or radial runout of wheel or tire. | * BALANCE the wheel and tire assemblies. Using a suitable dial indicator gauge and holding fixture, CHECK lateral and radial runout of the wheel and tire assemblies. INSTALL new wheel and tire assemblies as necessary. REFER to: (204-04 Wheels and Tires) Specifications (Specifications), Wheel and Tire (Removal and Installation). | | Wobble or shimmy affecting wheel runout | * Damaged wheel. | * INSPECT the wheel rims for damage. BALANCE the wheel and tire assemblies. Using a suitable dial indicator gauge and holding fixture, CHECK lateral and radial runout of the wheel and tire assemblies. INSTALL new wheel and tire assemblies as necessary. REFER to: (204-04 Wheels and Tires) Specifications (Specifications), Wheel and Tire (Removal and Installation). | | * Front wheel bearing. | * CHECK or INSTALL new wheel bearings as necessary. REFER to: Front Wheel Bearing (204-01 Front Suspension, Removal and Installation). | | Excessive vehicle vibration, rough steering | * Suspension components. | * CHECK or INSTALL new suspension components as necessary. | | Vehicle vibrations from wheels and tires | * Incorrect tire pressure(s). | * ADJUST the tire pressure(s). | | * Wheel or tire imbalance. | * BALANCE the wheel and tire assemblies. | | * Uneven tire wear. | * INSTALL a new tire(s) as necessary. REFER to: Wheel and Tire (204-04 Wheels and Tires, Removal and Installation). | | * Brake disc imbalance. | * CHECK the brake disc for foreign material. | | * Water in tire(s). | * REMOVE the water. | | * Bent wheel. | * INSTALL a new wheel and tire assembly. REFER to: Wheel and Tire (204-04 Wheels and Tires, Removal and Installation). | | * Incorrectly seated tire bead. | * SPIN the wheel on the vehicle. EXAMINE the area where the tire and the wheel meet. If that section of the tire appears to waver while being rotated, the tire bead may not be correctly seated on the wheel. REMOVE the tire and CLEAN the bead seat areas on both wheel and tire. | | * Excessive lateral or radial runout of wheel or tire. | * BALANCE the wheel and tire assemblies. Using a suitable dial indicator gauge and holding fixture, CHECK the lateral and radial runout of the wheel and tire assemblies. INSTALL new wheel and tire assemblies as necessary. REFER to: (204-04 Wheels and Tires) Specifications (Specifications), Wheel and Tire (Removal and Installation). | | * Foreign material between wheel mounting face and hub mounting surface. | * CLEAN mounting surfaces. | | * Front wheel bearing. | * CHECK or INSTALL new wheel bearings as necessary. REFER to: Front Wheel Bearing (204-01 Front Suspension, Removal and Installation). | | Rust streaks from the wheel stud holes in the wheel | * Wheel nuts. | * REMOVE the wheel and tire assembly. Inspect the wheel nuts and wheel and tire assembly for damage. INSTALL new wheel nuts and wheel and tire assemblies as necessary. REFER to: (204-04 Wheels and Tires) Specifications (Specifications), Wheel and Tire (Removal and Installation). | | Seized wheel nuts | * Corrosion. | * CAUTION: Do not permit lubricant to get on cone sets of stud holes or on cone angle of wheel nuts. If corrosion is slight, wire brush away. If corrosion is excessive, INSTALL new wheel studs and nuts. REFER to: (204-04 Wheels and Tires) Specifications (Specifications), Wheel and Tire (Removal and Installation). If the condition persists, LUBRICATE the first three threads of each wheel stud with a graphite-based lubricant. | | * Vehicle overloaded | * CORRECT as necessary. | |
