Tire and Gear Ratio

Some one was asking about how to tell what size gears one would want when changing tire sizes - here's the formula via Four Wheeler Magazine..

tire diameter=mph x rear end ratio x transmission ratio x 336 / engine rpm

x is multiply
/ is divide

this formula would determine at what rpm you want the engine to be turning at a given vehicle speed

depending on the tire size - -this should help you determine desired tire size/gears

you can also use the quick method. if you start off with a 4.10 ratio with a 31 inch tall tire, a 32 inch tire will drop ratio to 4.00, a 33 inch tall tire will be a 3.90 gear ratio, ect.