Mechanics

CHEVY SPEEDOMETER

2007 Chevrolet Truck

Tires and Wheels problem
2007 Chevy Truck V8 Four Wheel Drive Automatic 35000 miles

we put new oversized 331250 toyo tires on the truck and belive the speedometer or calibration is off. What is the digistonic of how this can be checked. What steps need to be done? Thanks
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Toreyandsuzanne
December 12, 2008.



There is really not much you can do. Here is a bulletin outlining aftermarket wheels. The 2500 series trucks have LT245/75R16E tires as standard equipment.

• The 3500 series trucks with dual rear wheels have LT215/85R16D tires as standard equipment.

• The 3500 series trucks with single rear wheels have LT265/75R16E 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, cruise control concerns and increased steering effort, especially during parking lot maneuvers at slow speeds.

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.

I know this is something you may not want to hear but these are the problems you will encounter. It's a shame you spent all that money on nice wheels and tires and will have nothing but trouble.

Brian 1
Dec 12, 2008.