Stock 17's to Stock 18's

[GTO 1]

The 17's seem to be taller than the stock 18 combo. If I upgrade to the 18's what will I have to do to to recalibrate the speedo/computer ect.? Can the dealer do this for me so all matches as if it came from the factory with 18's?
Thanks...

[abepro]

The difference is pretty minimal, I hadn't heard of people changes anything when they switch tires.. I don't think there is any difference from the factory. I could be wrong though.. I plugged the tires into one of those calculators to see the difference..

http://img223.imageshack.us/img223/804/tireshg6.pn g

[caritter3]

I think the difference is soo minimal you don't need to worry. Abepro's attachment only shows a difference of 9 revolutions per mile which is a little under 60 feet. This is only 1.14% of a mile, and I doubt GM does anything different when building a 17" rim car compared to a 18" rim car.

[GTO 1]

That calculator is perfect for for what I wanted to know. Thanks to BOTH of your responses!! I thought is was a LOT of difference. Seems someone on here had both "sise by side" and it was noticable. Maybe his were not stock sizes.. Again thanks!!!!!!!!!!!!!!