Diagnostic Tips for Tire Vibration or Steering Wheel Shake (Oscillation) Concerns

This bulletin is being revised to change the Subject line and add the 2008 model year. Please discard Corporate Bulletin Number 02-03-10-005A (Section 03 -- Suspension).

This bulletin is being issued to assist technicians in efficiently diagnosing and correcting tire vibration or steering wheel shake (oscillation) concerns. This steering wheel shake or tire vibration is most often noticed while driving at highway speeds (typically between 92-105 km/h (57-65 mph)) on smooth roads. The most common contributor of this steering wheel shake or tire vibration is front tire/wheel assembly imbalance or out-of-round.

When tires are out of round, several types of shake can occur. A common measure of "out-of-round" is runout. Some parts that commonly shake with out of round tires include the cab and seats, the hood, and the steering wheel. There are several factors that can cause runout.

In addition to the individual parts, the way these parts mount to each other can affect total runout. For example, the tire may not be properly seated on the wheel. Another example is when the hub is not rotated so that one of the four hub pilot pads is at the top when the wheel nuts are tightened. If two hub pilot pads are at the 10 o'clock and 2 o'clock positions, the wheel will be poorly centered on the hub.

When a vehicle is identified with a steering wheel shake or tire vibration condition, it is recommended that the check procedures listed below be followed in the indicated order.

Preliminary Checks

Important: These vehicles are incomplete when they leave the assembly plant; the vocational body has not been installed. The incomplete vehicle may exhibit some vehicle or driving characteristics that could be deemed objectionable. When the vocational bodies are installed and the vehicle is in its completed state; these characteristics tend to go away. For this reason, no attempt should be made to diagnose or repair driveline or steering vibration concerns until the vocational body has been installed.

1. Visually inspect the tires and the wheels. Inspect for evidence of the following conditions and correct as necessary.

•	Missing balance weights

•	Bent rim flange

•	Irregular tire wear

•	Tire irregularities

•	Mud/ice build-up in the wheel

2. Check and adjust the tire pressures. Be sure they are the same on both sides, appropriate for the load and within the specified pressure range.
3. Evaluate the vehicle on a smooth road at 97 to 105 km/h (60 to 65 mph) for at least 3.2 km (2 mi). Observe the condition. Note the amount of steering wheel rim motion when lightly holding the steering wheel. Use this dimension as a baseline. If the speed commented by the customer is near 97 km/h (60 mph), use the speed defined by the customer. If the speed is less than 80 km/h (50 mph), the condition is likely not related to tire/wheel assembly runout. In this case, refer to Vibration Diagnosis and Correction in service information (SI).

Checking for Proper Tire to Wheel Mounting (Bead Seating)

1. Raise both front tires off the ground and secure the vehicle with jack stands or another appropriate safety device. There are molded rings on the tire near the outer edge of the rim. Measure and record the distance from the rim to one of the rings. Make this measurement at 8 points around the wheel. The distance from the wheel to one of these rings should not vary more than 1.59 mm (0.0625 in). The outer and inner surfaces should be checked on both front wheels. If they are within 1.59 mm (0.0625 in), go to Front Tire/Wheel Assembly Matching to Hub, step 1.
2. If the tire to wheel mounting needs correcting, do the following steps:

2.1.	Remove the tire/wheel assembly.

2.2.	Deflate the tire.

2.3.	Unseat the tire/wheel beads.

2.4.	Lubricate both the wheel and tire, then re-inflate.

2.5.	Check the wheel to mold ring dimensions again. If not within 1.59 mm (0.0625 in), repeat these steps.

If proper seating cannot be achieved, replace the tire.

3. Reinstall the tire/wheel assembly using the following steps.

Front Tire/Wheel Assembly Matching to Hub

1. Rotate both front hubs until one of the hub pilot pads on each hub is at the 12 o'clock position.
2. Loosen the wheel nuts a few threads so the wheel can rock slightly or install the tires, if removed to correct improper mounting (above), and install the wheel nuts until they are a few threads from being fully seated.
3. Rotate the hub until any one of the hub pilot pads is at the 12 o'clock position. Carefully tighten at least two of the wheel nuts, directly across from each other, while keeping the hub pilot pad at 12 o'clock. If the tire high point can still be seen on the tire (this will be a red paint dot for Michelin and Bridgestone/Firestone tires, and it will be a yellowish-green sticker on the Goodyear tires, as placed on the tire by the tire manufacturers), then ensure that the tire high point is placed at the 12 o'clock position (or, minimally, between the 11:00 and 1 o'clock positions) while ensuring that one of the hub pilot pads is at 12 o'clock.
4. Tighten all wheel nuts following the recommended sequence defined in Tire and Wheel Removal and Installation in SI.

Rear Tire/Wheel Assembly Matching to Hub

1. This step is important because it can affect the runout of both the inner and outer wheels at the same time. Lift the rear axle so that both tires are off the ground. Rotate the left rear hub until one of its hub pilot pads is at the 12 o'clock position. Due to the differential, complete the steps on one side before working on the other side.
2. Loosen the left rear wheel nuts a few threads so the inner and outer wheels can rock slightly. If the inner and outer wheels do not rock easily, remove the wheels from the hub and re-install.
3. Carefully tighten at least two of the wheel nuts, directly across from each other, while keeping the hub pilot pad at 12 o'clock.
4. Tighten all wheel nuts following the recommended sequence defined in Tire and Wheel Removal and Installation in SI.
5. Rotate the right rear hub until one of its hub pilot pads is at the 12 o'clock position.
6. Loosen the right rear wheel nuts a few threads so the inner and outer wheels can rock slightly. If the inner and outer wheels do not rock easily, remove the wheels from the hub and re-install.
7. Carefully tighten at least two of the wheel nuts, directly across from each other, while keeping the hub pilot pad at 12 o'clock.
8. Tighten all wheel nuts following the recommended sequence defined in Tire and Wheel Removal and Installation in SI.
9. Drive the truck and evaluate at speeds as defined by the customer. It is not necessary to exceed 113 km/h (70 mph).

Normally, the above steps will be sufficient. If not, perform the following steps:

1. Check the rear tire to wheel mounting as in the Checking for Proper Tire to Wheel Mounting section above. If a concern still exists, go to the next step.
2. Lift the front axle so that both tires are off the ground.
3. Measure the radial runout with a dial indicator. Mark the high spot on the sidewall of each front tire/wheel assembly. Note: If a Hunter GSP9700 Road Force Measurement Machine is available, it may be used to match mount the tire to the wheel and to determine the high spot of the assembly.
4. Remove both front tire/wheel assemblies and dynamically balance them.
5. Rotate both front hubs until one of the hub pilot pads on each hub is at the 12 o'clock position.
6. Install the tire/wheel assembly on each side so that the high spot is between the 11 and 1 o'clock positions, while making sure the hub pilot pad is at 12 o'clock.
7. Carefully tighten at least two of the wheel nuts, directly across from each other, while keeping the hub pilot pad at 12 o'clock.
8. Tighten all wheel nuts following the recommended sequence defined in Tire and Wheel Removal and Installation in SI.
9. Drive the truck and evaluate at speeds as defined by the customer. It is not necessary to exceed 113 km/h (70 mph).
10. If the issue is not resolved, contact Technical Assistance.