All you do is go into the custom tune menu and find the adjustment for wheels and tires. then you simply adjust the bar to the number closest to the ratio you have. it says right in the instruction book how to do it. or if you've lost the book, you can download it at www.diablosport.com
A forum community dedicated to Ford Mustang owners and enthusiasts. Come join the discussion about performance, builds, modifications, reviews, engine swaps, classifieds, troubleshooting, maintenance, and more!