Caution: Failure to adhere to the following precautions before tire balancing can result in personal injury or damage to components:

Important: The tires can be balanced either on-vehicle or off-vehicle, but the off-vehicle balancing procedures are recommended. Off-vehicle methods are better because tire rotation will not affect the balancing. The off-vehicle balancers are also more accurate than the on-vehicle balancers. Off-vehicle balancers can perform dynamic balancing as well as static balancing.

Tire and wheel balancers can drift out of calibration without warning, or can become inaccurate as a result of abuse. The balancer calibration should be inspected every two weeks, and whenever the readings are questionable.

1. Spin the balancer without a wheel or any of the adapters on the shaft.
2. Inspect the balancer readings.

Specification
0.00-0.25 oz

3. Balance a tire and wheel assembly that is within radial and lateral tolerances to ZERO.
4. Add a 3 ounce test weight to the wheel at any location.
5. Spin the tire and wheel assembly again, noting the readings.

•	In the static and dynamic modes, the balancer should call for 3 ounces of weight, 180 degrees opposite the test weight.

•	In the dynamic mode only, the weight should be called for on the flange of the wheel opposite the last weight.

6. With the assembly unbalanced to 3 ounces, cycle the balancer 5 times.
7. Take the balancer readings:

Specification
Variation: 0.25 oz or less

8. Index the tire and wheel assembly at four separate locations on the balancer shaft, 90 degrees apart.
9. Cycle the balancer with the assembly at each location.
10. Take the balancer readings:

Specification
Variation: 0.25 oz or less

Static and dynamic balance are two kinds of tire/wheel balance:

Most off-vehicle balancers are capable of checking both types of balance simultaneously.

As a general rule, most vehicles are more sensitive to static imbalance than to dynamic imbalance, with as little as 0.50-0.75 ounce capable of inducing a vibration in some vehicles. Vibration induced by static imbalance will cause a vertical or BOUNCING motion of the tire.

Dynamic imbalance results in a side-to-side motion of the tire. This motion is referred to as SHIMMY.

On-vehicle imbalance may result from components other than the tire and wheel assemblies having imbalance. An on-vehicle high-speed balance or replacement of suspected components may be necessary in order to correct the condition.

Rotors do not have a set tolerance. However, rotors with more than 0.75 ounce imbalance have the potential to cause vibration. The rotors can be inspected for imbalance using either the on-vehicle or the off-vehicle method as described below:

1. Support the vehicle rear axle on a suitable hoist. Refer to Lifting and Jacking the Vehicle in General Information.
2. Remove the rear tire and wheel assemblies. Refer to Wheel Removal 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. Take the necessary precautions.
5. Run the vehicle at the complaint speed while inspecting for vibration.
6. If the vibration still exists, perform the following steps:

6.1.	Remove the rotors.

6.2.	Run the vehicle back to speed.

7. If the vibration is eliminated, perform the following steps:

7.1.	Remove the rotors one at a time.

7.2.	Perform the vibration test for each rotor.

7.3.	Replace the rotor causing the imbalance.

7.4.	Inspect the balance of the new rotor.

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 only be inspected for static imbalance. Ignore the dynamic imbalance reading.

3. Inspect for static imbalance.

The vibration problem may not be correctable with the components removed from the vehicle. An on-vehicle high-speed balancer may be required in order to balance the tire and wheel assemblies while still mounted on the vehicle. On-vehicle balancing will balance the hubs and the rotors simultaneously, and will compensate for any residual runout encountered as a result of mounting the tire and wheel assemblies on the vehicle as opposed to off-vehicle balancing.

Follow the on-vehicle balancer manufacturer operator's manual for specific instructions while keeping the following tips in mind:

Radial force variation is the difference in the stiffness of a tire as the tire rotates and contacts the road. The tire and wheel assemblies have some variation due to splices in the tire plies. These splices do not cause a problem unless the force variation is excessive. These STIFF SPOTS in the tire (1) can deflect the tire and wheel assembly upward as the assembly contacts the road.

If the tire has only one stiff spot, the spot will deflect the spindle once per each revolution of the tire and wheel assembly, thus causing a first-order tire/wheel vibration. If the tire has two stiff spots, the spots cause a second-order vibration. First- and second-order tire/wheel vibrations are the most common to occur as a result of radial force variation. Third-, fourth-, or higher orders are possible but rarely occur.

The most effective way to minimize the possibility of force variation as a factor in tire and wheel assembly vibrations is to ensure that the tire and wheel assembly runout is at an absolute minimum. However, some tire and wheel assemblies exhibit vibration-causing force variation even though they are within runout and balance tolerances. These instances are becoming rare due to tighter tolerances and higher standards in manufacturing.

The following two alternatives are available if force variation is suspected as a factor in tire and wheel assembly vibration complaints:

The tires may be buffed on a tire matching machine that is designed to remove small amounts of rubber from the outer rows of the tread blocks at the location of the stiff spots under load. This eliminates the spindle deflection. This type of equipment is not currently in widespread use. Do not use a TRUER or any tool that is designed to make the tire perfectly round. These tools will not correct the condition.

You may substitute one or more known good tire and wheel assemblies when a tire manufacturer is not available locally.

Lateral force variation tends to deflect the vehicle sideway, or laterally. Lateral force variation is based on the same concept as radial force variation. A SNAKY belt inside the tire may be the cause of lateral force. The tire substitution method may have to be used before tire replacement.

A lateral force variation condition is rare. The best way to eliminate lateral force variation as a factor in tire and wheel vibration conditions is to ensure that the lateral runout of the tire and wheel assemblies is at an absolute minimum.

The vehicle will WOBBLE or WADDLE at slow speeds of 8-40 km/h (5-25 mph) when lateral force variation is excessive. This condition is usually related to the first-order of tire and wheel rotation.

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, the axle flange, or the 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: 0.130 mm (0.0050 in)

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 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: 0.80 mm (0.030 in)