|When entering tire diameters, take into consideration the static loaded radius of the tire, not the overall manufacturers published diameter. For example, at correct pressure, my 32" BFG Mud Terrains have a static loaded radius of 14.625 inches. This gives an effective diameter of 29.25 inches.
For accurate results, measure from the ground to the center of the axle, and multiply by 2 then enter that value into the calculators.
This height can change depending on tire pressure (aired up on the street, and aired down off-road) and the speed of the vehicle (centrifugal force on the tire carcass).
These calculators are based on code created by Mark
Medina - http://www.4lo.com/