Initial Inspection and Diagnostic Overview

Special Tools:

Special Tool(s)

Inspection and Verification

WARNING: A vehicle equipped with a Traction-Lok differential will always have both wheels driving. If, while the vehicle is being repaired, only one wheel is raised off the floor and the rear axle is driven by the engine, the wheel on the floor can drive the vehicle off the stand or jack. Be sure both rear wheels are off the floor. Failure to follow these instructions may result in personal injury.

WARNING: Never run the engine with one wheel off the ground, for example, when changing a tire. The wheel(s) resting on the ground could cause the vehicle to move. Failure to follow these instructions may result in personal injury.

WARNING: Do not balance the wheels and tires while they are still mounted on the vehicle. Possible tire disintegration or differential failure can result, causing serious injury and extensive component damage. Use off-vehicle wheel and tire balancer only. Failure to follow these instructions may result in personal injury. Be sure to follow the warnings when carrying out inspection and verification.

CAUTION: Reduce the air pressure as much as possible by pushing the valve core plunger in prior to removing the valve core. Avoid working in a position in which the face or body is directly over a tire in which there is pressure. When carrying out any inspection or repair procedures on wheels and tires, follow the preceding safety precautions.

Road Test
Verify the customer concern by carrying out a road test on a smooth road. If any vibrations are apparent, refer to Noise, Vibration and Harshness Diagnosis.

To maximize tire performance, inspect for signs of incorrect inflation and uneven wear which can indicate a need for balancing, rotation or a suspension alignment.

Correct tire pressure and driving techniques have an important influence on tire life. Heavy cornering excessively rapid acceleration and unnecessary sharp braking increase tire wear.

Replacement tires should follow the recommended:
- tire sizes
- speed rating
- load range
- tire construction type

Use of any other tire size or type may seriously affect:
- ride
- handling
- speedometer/odometer calibration
- vehicle ground clearance
- tire clearance between the body and chassis
- wheel bearing life
- brake cooling

Wheels need to be replaced when:
- bent
- dented
- cracked
- heavily corroded
- leaking
- they have elongated wheel hub bolt holes
- they have excessive lateral or radial runout

Wheel and tire assemblies are attached by five wheel nuts

It is mandatory to use only the tire sizes recommended on the tire chart attached to the vehicle. Larger or smaller tires can damage the vehicle, affect driveability and require changing the speedometer calibration. Make sure wheel size and offsets match those recommended for the tire in use.
1. Inspect for signs of uneven wear that can indicate a need for balancing, rotation, suspension alignment, or damaged steering components.
2. Check tires for:
- cuts
- stone bruises
- abrasions
- blisters
- embedded objects
3. Tread wear indicators are molded into the bottom of the tread grooves. Install a new tire when the indicator bar becomes visible.

Match Mounting Tires
Match mounting is a technique used to reduce radial runout. Excessive runout is a source of vibration, shimmy and poor handling concerns. Use the following steps to reduce radial runout:
1. Mark the wheel at the same point as the mark previously made when measuring the tire runout.
2. Dismount the tire and remount it 180 degrees on the wheel so the original mark on the tire is opposite the mark on the wheel.
3. Inflate the tire to specification.
4. Measure the radial runout with Radial Runout Gauge at the center of the tread face.
If the radial runout is reduced to acceptable guide lines, the tire can be used. If the radial runout remains excessive, check the wheel runout.

Tire Lead Diagnosis
Lead is the deviation of the vehicle from a straight path on a level road with no pressure on the steering wheel. Lead can be caused by:
- incorrect wheel alignment
- dragging brakes
- incorrect/uneven tire pressure
- defective tires

If defective tires are suspected in a lead condition, use the following steps to determine the defective tire:
1. Rotate the two front tires.
2. Road test the vehicle. If the vehicle leads to the opposite direction, one of the front tires is at tumult.
3. Rotate the two front tires back to their original position.
4. Rotate one of the front tires with its corresponding rear tire on the same side of the vehicle.
5. Road test the vehicle. If the lead is corrected, install a new rear tire. If the lead remains, install a new front tire on the opposite side of the vehicle.