For 1990-2009 cars

# EI07266 - Vehicle/Tire Vibration, P275/55R20, LT245/75R16, P265/70R17, P245/70R17 - Diagnostic Information to Reduce Vibration Concerns)

Subject: | EI07266 -- Vehicle/Tire Vibration, P275/55R20, LT245/75R16, P265/70R17, P245/70R17 -- Diagnostic Information to Reduce Vibration Concerns

Models: | 2007-2008 GM Passenger Cars and Light Duty Trucks (including Saturn)

| 2007-2008 HUMMER H2, H3

| 2007-2008 Saab 9-7X

| with any of the following Tire RPOs:

| - QSS (P275/55R20)

| - QIZ (LT245/75R16)

| - QAS / QAN (P265/70R17)

| - QJM / QJP (P265/70R17)

| - QPR (P245/70R17)

| - QVL (P265/70R17)

| - QST (P285/45R22)

| - QXT (LT265/75R17

This bulletin is being revised to add models/tires and end the need for diagnostic information and provide guidance on tire and wheel issues. Please discard Corporate Bulletin Number 07-03-10-013B (Section 03 -- Suspension).

Some customers may comment on a vehicle/tire vibration.

### Diagnostic Information

Based upon feedback from dealers, GM engineering has made the following recommendations:

1. Before performing any repairs, duplicate the customer's concern AND test drive the vehicle for 16-24 km (10-15 mi) to properly warm up tires, and remove any temporary flat spots. Refer to Corporate Bulletin Number 03-03-10-007C.
2. Prior to taking any Road Force Variation (RFV) measurements, it is important to clean the inner wheel surface and remove any large stones from the tire tread. If the tire and wheel assembly is 1-10 lbs greater than GM guidelines for RFV, tire-to-wheel match mounting per Document ID # 1579478 should be attempted. Tire and Wheel Balancing Guidelines-Off Vehicle, refer to Document ID # 1579474, for on-vehicle balancing, refer to Document ID # 1579476.
3. Road Force Variation (RFV) guidelines can be found in SI. Refer to Information on Tire Radial Force Variation (RFV), Bulletin Number 00-03-10-006.
4. If all assemblies can be balanced and RFV readings are within GM Guidelines, runout measurements should be taken to further assist in diagnosis.
5. If the tire is condemned, all findings (including Position on vehicle, out of balance, RFV and Runout) must be documented on the R.O. and Global Tire Warranty Return form.
6. After installing a new tire, perform a Road Force Variation (RFV) test again to make sure the new tire assembly is within guidelines.
7. Remember that heavy-duty pickup trucks vibrate when not under a load.
8. Refer to Corporate Bulletin Number 08-03-10-004 for GM guidelines on balancing weights. There is a maximum limit of 5 oz per flange.
9. Take measures to avoid flat-spotting by keeping the PSI high prior to delivery.