Tire size and speedo

zorrro · June 4, 2004

What's with the tire size and speedo reprogramming? It sounds like the guys with the Westers can just do this at will. Do you have to use a Westers or similar to do this? Can your local dealer reprogram your speedo to match tire size w/o buying an after market tuner? Can the factory PCM be reprogrammed for tire size by the owner?

Thanks...............Zorrro

Wingnut · June 4, 2004

Depends on the size of the tires. Your dealer can reprogram up to 265/75/16s, but if you go 285 and up, you will need an aftermarket programmer. Like PCMforless.com (site sponsor here), Westers, Nelsons, or a variety of handhelds.

Some of the handhelds will let you do it yourself, along with a host of other things.

Most of the guys here are swearing by the custom tunes provided by Westers, Nelsons, and PCMforless...They say that they are leaps and bounds above what you'll get with a handheld.

snoman · June 4, 2004

Depends on the size of the tires. Your dealer can reprogram up to 265/75/16s, but if you go 285 and up, you will need an aftermarket programmer. Like PCMforless.com (site sponsor here), Westers, Nelsons, or a variety of handhelds.

Some of the handhelds will let you do it yourself, along with a host of other things.

Most of the guys here are swearing by the custom tunes provided by Westers, Nelsons, and PCMforless...They say that they are leaps and bounds above what you'll get with a handheld.

Yes and no. If the dealer tech is really sharp they can juggle tire size and axle ratios to get your speedo correct in all but extreme cases.