At this point in the process of diagnosing the vibration; the vibration has been duplicated and the frequency of the vibration has been determined to be related to the tire and wheel rotating components group, or vehicle speed sensitive.

(If these determinations have not yet been made, refer to Classifying the Vibration before proceeding.)

The following specific vehicle components will now be addressed according to vibration frequency and symptoms:

The following are symptoms of vibrations caused by tire/wheel assemblies:

A first order tire and wheel vibration is usually the result of one of the following five conditions:

These conditions must be eliminated one at a time in order to attain a set of tires that are free from vibration causing elements. Substitute a set of tires from another vehicle ONLY as a last resort, and ONLY after the tires have been tested on a similar vehicle under the same conditions. Correcting the existing tire and wheel assemblies is the most accurate and least time consuming approach. This is due to vehicle-to-vehicle sensitivities and the differences between the hubs of any two vehicles.

Important: In order to avoid back-tracking and/or unnecessary repairs, proceed through the diagnosis of tire and wheel assembly vibrations step by step and in order as called out by each step.

Prior to removing the tire and wheel assemblies from the vehicle, perform the following visual inspections:

1. Inspect the front and rear suspension components for wear and/or damage. Replace worn or damaged parts as necessary, then perform a wheel alignment as necessary.
2. Check the tire inflation pressures. Adjust the tire inflation pressures to specifications if necessary.
3. Closely inspect the tires for the following conditions:

•	Excessive wear

•	Irregular wear

•	Tread distortions or separations

•	Sidewall bulges; possible impact damage (slight sidewall indentations are normal ply splices)

4. If any of the tires exhibit any of these conditions, replace the worn or damaged tire(s).
5. Closely inspect the wheel rim flanges for any signs of impact damage and for loose or missing wheel weights.

If any or the wheels exhibit severe damage, replace the damaged wheel(s).

6. If any of the tires and/or wheels were replaced, proceed to Off-Vehicle Runout Check, below.
7. If NO excessive wear, unusual wear, or damage was found in any of the components inspected, proceed to On-Vehicle Runout Check, below.

If the vehicle has been sitting in one place for an extended period of time, the tires may develop flat spots at the point where the tires were resting on the ground. These flat spots will affect the runout readings. In order to eliminate these flat spots, drive the vehicle long enough to warm up the tires. The flat spots must be eliminated prior to taking any runout measurements.

Prior to removing the tire and wheel assemblies from the vehicle, perform the following:

1. Closely inspect each tire for proper and even bead seating.
2. If any of the tire beads are not properly or evenly seated, reseat the tire bead (refer to Tire Mounting and Dismounting , or Tire Mounting and Dismounting in Tires and Wheels), then proceed to step 3.
3. Prepare the vehicle and measure the runout of each tire and wheel assembly, refer to Tire and Wheel Runout Measurement .
4. If the on-vehicle runout measurement of the tire and wheel assemblies ARE within specifications, proceed to Tire and Wheel Balancing .
5. If the on-vehicle runout measurement of the tire and wheel assemblies ARE NOT within specifications, proceed to Off-Vehicle Runout Check, below.

If the vehicle has been sitting in one place for an extended period of time, the tires may develop flat spots at the point where the tires were resting on the ground. These flat spots will affect the runout readings. In order to eliminate these flat spots, drive the vehicle long enough to warm up the tires. The flat spots must be eliminated prior to taking any runout measurements.

1. Prior to removing the tire and wheel assemblies from the vehicle, mark the location of the wheels to the wheel studs and mark the specific vehicle position on each tire and wheel (LF, LR, RF, RR).
2. Remove the tire and wheel assemblies from the vehicle.
3. Closely inspect each tire for proper and even bead seating.
4. If any of the tire beads are not properly or evenly seated, reseat the tire bead (refer to Tire Mounting and Dismounting , or Tire Mounting and Dismounting in Tires and Wheels), then proceed to step 5.
5. Measure the runout of each tire and wheel assembly, refer to Tire and Wheel Runout Measurement .
6. If the off-vehicle runout measurement of the tire and wheel assemblies ARE within specifications, proceed to Tire and Wheel Mounting Inspection, below.
7. If the off-vehicle runout measurement of the tire and wheel assemblies ARE NOT within specifications, replace the tire(s) and/or wheel(s) as determined during the measurement, then recheck the runout to ensure that the tire and wheel assembly (assemblies) is (are) now within specifications, then proceed to step 8.
8. Balance the tire and wheel assembly (assemblies) which have had runout corrected and brought to within specifications. Refer to Tire and Wheel Balancing .

On-vehicle imbalance may result from components other than the tire and wheel assemblies -- hubs, rotors, drums -- having imbalance. It may be necessary to perform an on-vehicle, high-speed balance, or to replace the components suspected of being the cause.

Checking Rear Rotor Imbalance (On-Vehicle)

1. Support the vehicle rear (driving) axle on a suitable hoist or jackstands. Refer to Lifting and Jacking the Vehicle in General Information.
2. Remove the rear tire and wheel assemblies. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.
3. Reinstall the wheel nuts in order to retain the rotors.

Caution: One or more of the following guidelines may apply when performing specific required tests in the work stall:

•	When a test requires spinning the drive wheels with the vehicle jacked up, adhere to the following precautions:

-	Do not exceed 56 km/h (35 mph) when spinning one drive wheel with the other drive wheel stopped. This limit is necessary because the speedometer indicates only one-half the actual vehicle speed under these conditions. Personal injury may result from excessive wheel spinning.

-	If all of the drive wheels are spinning at the same speed, do not exceed 112 km/h (70 mph). Personal injury may result from excessive wheel spinning.

-	All persons should stay clear of the rotating components and the balance weight areas in order to avoid possible personal injury.

-	When running an engine in the repair stall for an extended period of time, use care not to overheat the engine and the transmission.

•	When a test requires jacking up the vehicle and running with the wheels and brake rotors removed, adhere to the following precautions:

-	Support the suspension at normal ride height.

-	Do not apply the brake with the brake rotors removed.

-	Do not place the transmission in PARK with the drive axles spinning.

-	Turn Off the ignition in order to stop the powertrain components from spinning.

•	When running an engine in the work stall, use the exhaust removal system to prevent breathing dangerous gases.

4. Run the vehicle at the complaint speed, and note if the vibration is still present.

4.1.	If the vibration is still present, remove the rear rotors and run the vehicle back up to the complaint speed.

4.2.	If the vibration is eliminated when the rotors are removed from the vehicle, perform the test with one rotor at a time. Replace the rotor which is causing the vibration.

Always check the new rotor for imbalance.

Checking Rotor Imbalance (Off-Vehicle)

Most brake rotors may be checked for imbalance using an off-vehicle balancer.

1. Measure the diameter and the width of the rotor.
2. Mount the rotor on a balancer in the same manner as a wheel.

Important: The rotors can be checked for STATIC imbalance ONLY. Ignore the dynamic imbalance readings.

3. Inspect the brake rotor for static imbalance.

There is not a set tolerance for rotor (or drum) static imbalance. (However, any brake drum/rotor measured in this same manner which is over ¾ ounce may have the potential to cause a vibration.) Rotors suspected of causing a vibration should be replaced. The new rotor should be checked for imbalance in the same manner.

Wheel Hub/Axle Flange Runout Check

Inspect the wheel hub/axle flange runout when lateral runout occurs during on-vehicle testing but not during off-vehicle testing. The tolerances provided are only guidelines. Perform corrections only if the on-vehicle runout cannot be brought to within tolerance.

1. Position the dial indicator on the machined surface of the hub, axle flange, or brake rotor, outside of the wheel studs.
2. Rotate the hub in order to find the low spot.
3. Set the dial indicator to zero at the low spot.
4. Rotate the hub again and check the total amount of runout.

Specification (Guideline)
Runout tolerance: 0.127 mm (0.005 in)

5. If the runout of the wheel hub/axle flange is within specification, proceed to Wheel Stud (Stud Circle) Runout Check, below.
6. If the runout of the wheel hub/axle flange is marginal, the wheel hub may or may not be the source of the vibration. Proceed to Radial/Lateral Force Variation Check, below.
7. If the runout of the wheel hub/axle flange is excessive, replace the wheel hub/axle flange. Check the runout of the new wheel hub/axle flange.

Wheel Stud (Stud Circle) Runout Check

Use the following procedure whenever the off-vehicle radial runout and the on-vehicle radial runout are significantly different, and earlier attempts to correct the tire and wheel vibration condition have not been successful.

1. Position the dial indicator in order to contact the wheel mounting studs.

Measure the stud runout as close to the flange as possible.

2. Turn the hub to register on each of the wheel studs.
3. Zero the dial indicator on the lowest stud.
4. Rotate the hub again and check the total amount of runout.

Specification (Guideline)
Runout tolerance: 0.254 mm (0.010 in)

5. If the runout of the wheel studs is within specification, proceed to Radial/Lateral Force Variation Check, below.
6. If the runout of the wheel studs is marginal, the wheel studs may or may not be contributing to the vibration. Proceed to Radial/Lateral Force Variation Check, below.
7. If the runout of the wheel hub/axle flange is excessive, replace the wheel studs as necessary. Check the runout of the new wheel studs.

Force variation refers to a radial or lateral movement of the tire and wheel assembly which acts much like runout, however, force variation has to do with variations in the construction of the tire which may actually cause vibration in a vehicle, even though the tire and wheel assembly runout and balance are within specifications.

Due to tighter tolerances and higher standards in manufacturing, these instances are becoming rare.

The most effective way to minimize the possibility of force variation as a factor in tire and wheel assembly vibration is to ensure that the tire and wheel assembly runout is at an absolute minimum (this tire and wheel vibration diagnostic process, if followed correctly, has already ruled-out runout and balance as contributing factors to the vibration).

Radial Force Variation Check

Radial force variation refers to the difference in the stiffness of a tire sidewall as the tire rotates and contacts the road. Tire and wheel assemblies have some stiffness due to splices in the different plies of the tire, but these stiffness differences do not cause a problem unless the force variation is excessive. These stiff spots (1) in the tire sidewall can deflect the tire and wheel assembly upward as the assembly contacts the road.

First- and second-order tire and wheel vibrations are the most common to occur as a result of radial force variation. Higher orders (third, fourth, etc.) are possible but rarely occur.

The following is the best method available to aid in determining if radial force variation is a factor in the vehicle tire and wheel vibration:

1. Substitute a set of known good tire and wheel assemblies (of the same size and type) for the suspected (original) assemblies. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.
2. Road test the vehicle to determine if the vibration is still present. Refer to Road Test .
3. If the vibration is still present, proceed to Wheel Alignment Check, below.
4. If the vibration is eliminated, install one of the original tire and wheel assemblies, using the matchmarks made prior to removal (refer to Tire and Wheel Removal and Installation in Tires and Wheels), then road test the vehicle to determine if the vibration has returned. Refer to Road Test .
5. Continue the process of installing the original tire and wheel assemblies one at a time, then road testing the vehicle, until the tire and wheel assembly (assemblies) which are causing the vibration have been identified.
6. Replace the tire(s) on the vibration causing tire and wheel assembly (assemblies). Refer to Tire Mounting and Dismounting , or Tire Mounting and Dismounting in Tires and Wheels.
7. Road test the vehicle to verify that the vibration has been eliminated. Refer to Road Test .

If some vibration is still present, proceed to Wheel Alignment Check, below.

Lateral Force Variation Check

Lateral force variation refers to the difference in the stiffness or conformity of the belts within a tire as the tire rotates and contacts the road. Tire belts have may have some stiffness or conformity differences, but these differences do not cause a problem unless the force variation is excessive. These variations in the belts of the tire can deflect the vehicle sideways or laterally. (A shifted belt inside a tire may cause lateral force variation.)

In most cases where excessive lateral force variation exists, the vehicle will display a wobble or waddle at low speeds (8 to 40 km/h [5 to 25 mph]) on a smooth road surface. This condition is usually related to first-order tire and wheel vibration.

The following is the best method available to aid in determining if lateral force variation is a factor in the vehicle tire and wheel vibration:

1. Substitute a set of known good tire and wheel assemblies (of the same size and type) for the suspected (original) assemblies. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.
2. Road test the vehicle to determine if the vibration is still present. Refer to Road Test .
3. If the vibration is still present, proceed to Wheel Alignment Check, below.
4. If the vibration is eliminated, install one of the original tire and wheel assemblies, using the matchmarks made prior to removal (refer to Tire and Wheel Removal and Installation in Tires and Wheels), then road test the vehicle to determine if the vibration has returned. Refer to Road Test .
5. Continue the process of installing the original tire and wheel assemblies one at a time, then road testing the vehicle, until the tire and wheel assembly (assemblies) which are causing the vibration have been identified.
6. Replace the tire(s) on the vibration causing tire and wheel assembly (assemblies). Refer to Tire Mounting and Dismounting , or Tire Mounting and Dismounting in Tires and Wheels.
7. Road test the vehicle to verify that the vibration has been eliminated. Refer to Road Test .

If some vibration is still present, proceed to Wheel Alignment Check, below.

1. Inspect the front and rear wheel alignment. Refer to Wheel Alignment Measurement and Wheel Alignment Measurement in Wheel Alignment.
2. If the front and rear wheel alignment is within specifications, proceed to Balancing Tires and Wheels (On-Vehicle), below.
3. If the wheel alignment is out of specifications, adjust the wheel alignment to within specifications. Refer to the following procedures as required:

•	Front Caster and Camber Adjustment in Wheel Alignment

•	Front Toe Adjustment in Wheel Alignment

•	Rear Camber Adjustment in Wheel Alignment

•	Rear Toe Adjustment in Wheel Alignment

4. Road test the vehicle to determine if the vibration is still present. Refer to Road Test .
5. If the vibration is still present, proceed to Balancing Tires and Wheels (On-Vehicle), below.

If after following this tire and wheel vibration diagnostic process, some amount of tire and wheel vibration is still evident, an on-vehicle high-speed spin balancer may be used (to perform an on-vehicle balance) in an attempt to finish balance the tire and wheel assemblies, wheel hubs and brake rotors simultaneously. On-vehicle balancing can also compensate for minor amounts of residual runout encountered as a result of mounting the tire and wheel assembly on the vehicle, as opposed to the balance which was achieved on the off-vehicle balancer.

If on-vehicle balancing is decided upon as an option, carefully consider the following information before proceeding:

In order to perform an on-vehicle balancing procedure, carefully follow the manufacturer's specific instructions while keeping the following tips in mind:

After completion of the on-vehicle balance, road test the vehicle to determine weather the vibration has been eliminated. Refer to Road Test .