USE OF NON-ORIGINAL SIZE TIRE AFFECT SPEEDOMETER & ODOMETER

As in the past, when tire sizes not recommended are used, the speedometer and odometer calibrations will be affected because these parts are calibrated to meet the original equipment tire sizes. On 1984 models with 1.8L or 2.5L engines and manual transmissions, the calibration of the shift light will also be affected.

Any time a non-recommended size tire is used, the customer should satisfy himself that tire clearance to the body will be sufficient, and should replace the speedo driven gear to correct speedometer and shift light calibration.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.