I know this isnt really engine tech but I just put 18" wheels with 225/40/18 tires and was wondering how to calibrate the speedometer for my car so that /i know how fast I am going. Any help would be great.

 

your speedo will only be a few mph off. I just did a quick check here http://www.miata.net/garage/tirecalc.html and it looks like you'll only be 3.6% off. So when your speedo is at 60, you'll be going 62.2, no big deal IMO

 

use stock sizes

 

Well, that was the whole purpose of getting bigger wheels..........The stock 15's on an Accord are not big enough to fill the wheel well up unless you put some nice balloon tires on them which handle "excellent". So using "stock sizes" in my part does not factor in. I can see using 15's on your Integra since the wheel wells are smaller and all but not for me.