Speedometer calibration

[thirdgoat]

I replaced tires on a 99 Tahoe, they were slightly oversized, and of course, the speedometer was off. I now have another set of tires (factory Silverado take-offs and wheels) that are P235, rather than the original 245's. Hey, brand new factory aluminum wheels and tires for $525 shipped, couldn't refuse! Anyway, I was wondering if disconnecting and reconnecting the battery to re-set the computer would have any effect on the speedometer at all. My speedometer still seems to read not correctly, and I have not had the chance to drive next to a known "good" speedometer in another vehicle.

Thoughts?

 

Thanks!

[Greg]

Cheapest solution: borrow a GPS unit from a friend, put in on top of the dash, and drive at different steady speeds you usually travel at. The GPS will give you the actual speed and you can keep the differences in you head.

[asepgrad98]

you can use the trip odometer and the mile markers on the interstate to find the %error of your odometer, that is the same %error of your speedo.

[Wingnut]

Unplugging you battery will do nothing at all to the speedometer.

 

The only way to change what size your computer thinks your tires are, is to have it reprogrammed.

 

Aftermarket tuner chips, custom tuners, speed shops, and dealerships are most of the ways that you can make these changes.

[capnfrantic]

Go here .

http://www.miata.net/garage/tirecalc.html

plug in sizes, look at variance.

[hercman]

I wonder if a tire revolves less per mile would that tire last longer then the smaller one. Hmm points to ponder.