how do you figure effective final drive ratio?

We may earn a small commission from affiliate links and paid advertisements. Terms

stmotorsports

Senior Member
ahh... yeah, what he said- how do you figure effective final drive ratio including overall wheel/tire diameter? So say going from a stock GSR 4.4:1 final with 205/50/15s (last year's setup) to say the JDM ITR 4.785 final and 205/45/16s (possibly next year's setup), what's the formula to compare the two in terms of what the 'real' difference will be?
 
Find your stock tire size and call that diameter a ratio of 1. Find out the diameter of the new tire you're going to use and vary that as a percentage of the original, multiply the percentage to get your new "final drive".
 
Back
Top