TSB 01-03-10-010B 2500 and 3500 series with larger than stock tires
The 2500 series trucks have LT245/75R16E tires as standard equipment.
The 3500 series trucks have LT215/85R16D tires as standard equipment.
A truck that has different tires and wheels will have Engine power/performance concerns, Transmission shift concerns, Speedometer registered speed concerns, and Cruise Control concerns.
Before any diagnosis is performed for these types of concerns, inspect the tires/wheels for the proper tire and wheel combinations.
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.
The Engine Control Unit (ECM) and Transmission Control Module (TCM) use (RPM) and (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.
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.
