WHEEL AND TIRES DIAGNOSIS/TESTING

id021200800900

Inspection/Verification

Warning

• A vehicle equipped with a traction-lock 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.

• 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.

• 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.

1. Be sure to follow the warnings when carrying out inspection and verification.

Road test

1. Verify the customer concern by carrying out a road test on a smooth road. If any vibrations are apparent, diagnose the area where is attributed to NVH.

2. To maximize tire performance, inspect for signs of suspension alignment, or damaged steering incorrect inflation and uneven wear. If there is any, indicate a need for balancing, rotation, or a suspension alignment.

3. 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.

4. Replacement tires should follow the recommended:

• tire sizes

• speed rating

• load range

• tire construction type

5. 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

6. 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

7. 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 road test 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

1. 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× 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 guidelines, the tire can be used. If the radial runout remains excessive, check the wheel runout.

Tire lead diagnosis

1. 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

• brake drag

• incorrect/uneven tire pressure

• defective tires

2. 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 fault.

(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.

Symptom Troubleshooting Chart

1. Verify the symptom, and conduct corresponding diagnosis.


Troubleshooting Item	Possible Cause	No.
Tires show excess wear on edge of tread.	• Underinflated tires • Vehicle overloaded • Incorrect wheel alignment • High-speed cornering • Incorrect tire rotation intervals	1
Tires show excess wear in center of tread.	• Overinflated tires	2
Other excessive/uneven tire wear problems (Except edge and center of tread)	• Improper tire pressure • Worn or damaged suspension components • Incorrect tire/wheel usage • Damaged, loose, or leaking shock absorbers • Incorrect wheel alignment • Wheel and tire assembly out of balance • Excessive lateral or radial runout of wheel or tire • Tires need rotating	3
Wheel mounting is difficult.	• Incorrect application or hub bolts and wheel nuts • Corroded, worn or damaged new parts	4
Wobble or shimmy	• Worn or damaged wheel bearings • Loose or damaged suspension components • Bent or damaged wheel • Wheel and tire assembly out of balance • Damaged tire • Loose wheel nuts	5
Vehicle vibrations	• Driveline. • Wheel and tire assembly out of balance.	6
High-speed shake	• Wheel hub face/pilot/bolt circle runout. • Wheel and tire assembly out of balance. • Damaged or worn wheel bearings. • Damaged or worn suspension/steering linkage. • Driveline. • Brake discs/imbalance.	7
Damaged wheel nuts	• Loose wheel assembly. • Overtightened wheel nuts.	8
Frozen wheel nuts	• Corrosion or galling. • Overloading.	9

No.1 Tires Show Excess Wear On Edge Of Tread.

Diagnostic procedure


STEP	INSPECTION		ACTION
1	Inspect the tire pressure. Is each tire pressure correct?	Yes	Go to the next step.
1	Inspect the tire pressure. Is each tire pressure correct?	No	Adjust the tire pressure.
2	Inspect for vehicle overloading. Is the vehicle under normal load?	Yes	Go to the next step.
2		No	Notify the customer of overload condition.
3	Inspect the wheel alignment. Is the wheel alignment correct?	Yes	Go to the next step.
3		No	Set the alignment to specification. (See FRONT WHEEL ALIGNMENT.) (See REAR WHEEL ALIGNMENT.)
4	Inspect for high-speed cornering. Is there no indication of high-speed cornering?	Yes	Go to the next step.
4		No	Return vehicle - Notify the customer of cause of condition.
5	Inspect the tire rotation interval. Is the tire rotation interval correct?	Yes	Vehicle is normal.
5		No	Advise the customer of condition. Rotate tires.

No.2 Tires Show Excess Wear In Center Of Tread.

Diagnostic procedure


STEP	INSPECTION		ACTION
1	Inspect tire pressure. Is the tire pressure correct?	Yes	Vehicle is normal.
1	Inspect tire pressure. Is the tire pressure correct?	No	Inspect the tire pressure.

No.3 Other Excessive (Except Edge and Center)/uneven Tire

Diagnostic procedure


STEP	INSPECTION		ACTION
1	Inspect the tire pressure. Is the tire pressure correct?	Yes	Go to the next step.
1	Inspect the tire pressure. Is the tire pressure correct?	No	Adjust the tire pressure.
2	Inspect wear and damage in the suspension components. Are the suspension components normal?	Yes	Go to the next step.
2		No	Inspect according to suspension system diagnosis/ test. (See SUSPENSION SYSTEM DIAGNOSIS/TESTING)
3	Inspect for correct tire and wheel usage. Is the tire and wheel usage correct?	Yes	Go to the next step.
3		No	Install the correct tire and wheel combination.
4	Inspect the shock absorbers. Are the shock absorbers normal?	Yes	Go to the next step.
4		No	Tighten or install new shock absorbers.
5	Inspect the wheel alignment. Is the wheel alignment correct?	Yes	Go to the next step.
5		No	Set the wheel alignment to the specifications. (See FRONT WHEEL ALIGNMENT.) (See REAR WHEEL ALIGNMENT.)
6	Inspect tire and wheel balance. Is the tire and wheel balance correct?	Yes	Go to the next step.
6		No	Balance the wheel and tire of balance. assembly.
7	Inspect tire and wheel runout. Is there any tire and wheel lateral or radial runout?	Yes	Advise the customer of the condition. Rotate the tires.
7		No	Vehicle is normal.

No.4 Wheel Mounting Is Difficult

Diagnostic procedure


STEP	INSPECTION		ACTION
1	Inspect hub bolts and wheel nuts. Are the hub bolts and wheel nuts correctly applied and matched?	Yes	Go to the next step.
1		No	Replace with correct parts.
2	Inspect hub bolts and wheel nuts. Are the hub bolts and wheel nuts normal?	Yes	The vehicle is normal.
2		No	Repair and replace hub bolt and wheel nut, as necessary.

No.5 Wobble or Shimmy

Diagnostic procedure


STEP	INSPECTION		ACTION
1	Inspect wheel bearings. Are the wheel bearings free of damage?	Yes	Go to the next step.
1		No	Install new wheel bearings.
2	Inspect any loose or damaged suspension components. Are the suspension components correct?	Yes	Go to the next step.
2		No	Repair or replace suspension components, as necessary.
3	Inspect the wheels. Are the wheels free of damage or bending?	Yes	Go to the next step.
3		No	Replace wheels, as necessary.
4	Inspect wheel and tire balance. Is the wheel and tire balance correct?	Yes	Go to the next step.
4		No	Balance the wheel and tire assembly.
5	Inspect the tires. Are the tires free of damage?	Yes	Go to the next step.
5	Inspect the tires. Are the tires free of damage?	No	Replace tires, as necessary.
6	Inspect wheel nuts. Are the wheel nuts tightened securely?	Yes	Vehicle is normal.
6	Inspect wheel nuts. Are the wheel nuts tightened securely?	No	Tighten to specification.

No.6 Vehicle Vibrations

Diagnostic procedure


STEP	INSPECTION		ACTION
1	Inspect the drive line. Is the drive line normal?	Yes	Go to the next step.
1	Inspect the drive line. Is the drive line normal?	No	Considered as a NVH concern. Repair or replace area where attributed to NVH.
2	Inspect wheel and tire balance. Is the wheel and tire balance correct?	Yes	Vehicle is normal.
2		No	Balance the wheel and tire assembly.

No.7 High Speed Shake

1. This is considered as a concern due to NVH. Identify NVH cause, and repair or replace.

No.8 Damaged Wheel Nuts

Diagnostic procedure


STEP	INSPECTION		ACTION
1	Inspect the wheel nuts. Is the wheel nut free of looseness?	Yes	Go to the next step.
1		No	Replace wheel. (See WHEEL AND TIRE REMOVAL/INSTALLATION.)
2	Inspect the wheel nuts. Overtightened wheel nuts?	Yes	Vehicle is normal.
2	Inspect the wheel nuts. Overtightened wheel nuts?	No	Remove the wheel nuts. Inspect for damage. Install new components as necessary.

No.9 Frozen Wheel Nuts

Diagnostic procedure


STEP	INSPECTION		ACTION
1	Inspect for frozen wheel nuts. Are the wheel nuts normal?	Yes	Go to the next step.
1	Inspect for frozen wheel nuts. Are the wheel nuts normal?	No	If the corrosion is slight, brush away the corrosion with a wire brush. If the corrosion is excessive, install new wheel studs and wheel nuts. If the condition persists, lubricate the first three threads of each wheel stud with a graphite-based lubricant Caution • Do not allow the lubricant to get on the cone seats of the stud holes or on the cone angles of the wheel nuts.
2	Inspect vehicle load condition. Is load condition normal?	Yes	Vehicle is normal.
2	Inspect vehicle load condition. Is load condition normal?	No	Adjust load volume, as necessary.