A/T - Shifting/Poor Performance
INFORMATIONBulletin No.: 01-03-10-010G
Date: July 22, 2009
Subject: Inspection of Tire and Wheel Size Prior to Diagnosis of Transmission Shifts, Poor Performance, Speedometer, Cruise Control Concerns
Models:
2001-2007 Chevrolet Silverado Pickup (Classic) Models Equipped with Allison(R) Automatic Transmission Only
2001-2007 GMC Sierra Pickup (Classic) Models Equipped with Allison(R) Automatic Transmission Only
2007-2010 Chevrolet Silverado Pickup HD Models
2007-2010 GMC Sierra Pickup HD Models
Supercede:
This bulletin is being revised to add the 2008-2010 model years, update the tire size information and reference the vehicle tire information label locations. Please discard Corporate Bulletin Number 01-03-10-010F (Section 03 - Suspension).
GM has developed and matched specific tires for your vehicle. The original equipment tires and their respective size installed on the vehicle when it was new, were designed to meet General Motors Tire Performance Criteria Specification (TPC Spec) system rating. GM's exclusive TPC Spec system considers over a dozen critical specifications that impact the overall performance of the vehicle.
A truck that has different tires and wheels from the original equipment designed for that vehicle will have engine power/performance concerns, transmission shift concerns, speedometer registered speed concerns, cruise control concerns and increased steering effort, especially during parking lot maneuvers at slow speeds.
The engine control module (ECM) and transmission control module (TCM) use engine speed (RPM) and vehicle speed sensor (VSS) inputs as operational parameters for engine torque, transmission shifting, cruise control operation and speedometer indicated vehicle speed.
Calibrations for different tire/wheel combinations are not available.
Therefore, changing of tire and/or wheel size should not be undertaken by dealerships or truck owners.
Proper diagnosis of engine, transmission, speedometer and cruise control concerns MUST begin with an inspection of tire/wheel size.
Important
A vehicle specific Tire and Loading Information label is attached to the center pillar (B-pillar) of the vehicle. With the driver's door open, you will find the label attached below the door lock post (striker). The label shows the size of the original equipment tires and the recommended cold tire inflation pressures.A vehicle specific Certification/Tire label is found on the rear edge of the driver's door. The label shows the size of the original equipment tires and the recommended cold tire inflation pressures.
2001-2007 Pickups (Classic) Equipped with Allison(R) Automatic Transmission Only
Inspect the vehicle for the proper tire size as indicated in the following information.
- The 2500 series trucks have LT245/75R16E tires as standard equipment.
- The 3500 series trucks with single rear wheels have LT265/75R16E tires as standard equipment.
- The 3500 series trucks with dual rear wheels have LT215/85R16D tires as standard equipment.
2007 Pickups HD Models (New Design Pickups)
Inspect the vehicle for the proper tire size as indicated in the following information.
- The 2500 series trucks have LT245/75R16E tires as standard equipment.
- The 3500 series trucks with single rear wheels have LT265/75R16E tires as standard equipment.
- The 3500 series trucks with dual rear wheels have LT215/85R16E tires as standard equipment.
2008-2010 Pickups HD Models (New Design Pickups)
Inspect the vehicle for the proper tire size as indicated in the following information.
- The 2500 series trucks have LT245/75R16E tires as standard equipment.
- The 3500 series trucks with single rear wheels have LT265/75R16E tires as standard equipment.
- The 3500 series trucks with dual rear wheels have LT225/75R17E tires as standard equipment.
If a truck is found to have other than the above listed tire sizes, no further diagnosis should be undertaken until the original size tires and wheels are reinstalled on the truck.
Warranty Information
Reinstalling the proper wheels and tires on the vehicle, prior to performing any type of diagnosis of the truck, would be considered truck owner responsibility and not a warranty repair.
Disclaimer