Just put 18s on - rear tire size is 295/35/18 and obviously my speedo is off..

the only option on my xcal3 that looks like it would fix this is tire revs/mile. Options are stock or 500-900 revs/mile incremented by 5. So how do I figure out what to set it on to make my speedo correct?

Thanks..

 

well just in case anyone else needs this info I figured it out. just used a little calculator I found on the internet

http://www.gordon-glasgow.org/tirecalc.html

 

Just as well, your speedo is off by maybe 2 MPH at 70.

 

Yeah dude. I would recommend the XCal3 or something along those lines. They allow you to account for any mods and will correct and dial in your speedo correctly. Some guy tried to sell me a car and the speedo kept getting more wrong as I got faster. It said 100KM/h while I was going 60. And plus, you dont want to be pulled over for something stupid like that. The added plus is that the tuner while give your car a boost in power. Its worth the buy in both terms. Best of Luck.

Mitch