Originally Posted by TxOutlaw
I know how to calculate it and all that, is that something I plug in or the person sending tunes does???
You can just tell the peson tuning it your mods and your tire size and they will set it up for you. In lieu of that you can input your tire revolutions in the SCT prior to actually flashing the custom program. Think it is under the program engine - options area. Be aware though that if you are going to use one of the "canned" tunes that come with the programmer I dont believe changing the tire revolutions option actually does anything. It will let you change the tire revolutions all day long but they dont have any effect on the speedo. I changed my stock tires from 560 revs to 510 revs when I was using the "street" tune and both of them were still off by 3 mph at 70 according to my gps.