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If putting a taller tire on a vehicle than stock, will that have an effect on gear ratio? So would putting a taller tire on make a car or truck with a 3:55 act like a 3:28? Would this result in better MPG?? Is there a calculator for this?? Thanks



Short answer: yes. You can calculat it from your starting point: Lets say you have 26" tires and 3.55 gears, and you're contemplating moving to a 28" tire. 26 x pi = 81.7" 28 x pi = 88.0" thats a 7.7% difference. (100-7.7) = 92.3 .923 (cause we're dealing with percentage) x 3.55 = 3.28

So a change from 26 to 28 in tire diameter would have the effect of going from a 3.55 gear to a 3.28. (some rounding error is present in the above exampple...but you get the idea)