04 Chevrolet Classic ZR2 Blazer Vibration at Highway Speeds - kw GMT330 wheel tire balance rough shake wobble

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Customers with the ZR2 suspension package and P265/75R15 tires may experience a vibration at highway speeds. This may be caused by the tires flat spotting as a result of tires reaching high temperatures and then cooling while parked.

Please review to bulletin 03-00-91-001B to make sure the tires are the cause of this vibration. A redesigned tire is available for this truck. To obtain a updated tire(s) P265/75R 15 for a service application, inspect the last 4 numbers of the DOT code. Tires manufactured after date code 2504, will be an updated tire. When ordering the tire(s), it is important to order the tire(s) by its article number from the tire manufacture or store. The article number is the manufactures part number. Order article number 1548080 to obtain the 265/75R 15 tire(s) with date code 2504 or higher. Tires ordered by the this article number will assure the correct tire(s) will be received. When replacing and balancing these tires, typical road force variations should be under 20lbs for the P265 series tire. After this road force is accomplished, test drive to confirm vibration has been eliminated.

Note: The DOT code is usually long in numbers and resides on the side wall of the tire. The last 4 numbers make up a julian date code. To explain the julian date code of 2504, the 25 equal the week of production and the 04 indicates the year of production. So the above date code consists of tires manufactured in the 25th week of 2004 or later.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

(2004 Chevrolet Blazer ZR2)

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