Enter the required Overall Width, Pinion Offset (location), Brake Space and Drum/Rotor thickness to find axle length and housing width
Differential Gear Ratio Calculator
Calculate your differential gear ratio from RPM, tire size and desired MPH

Enter the # of Pinion Gear teeth and the # of Ring Gear teeth to find the correct Rearend Gear Ratio for your Rig!
Find New Gear Ratio with New Tire Size
Buying bigger or smaller tires? Then you might need to change your gear ratio to keep up! Enter your new tire diameter, your old tire diameter and your present gear ratio to find out your new gear ratio
Convert P-Metric Tire to Tire Diameter Inches
Convert the funky P-Metric Tire # (Example: 195/75R15) on the side of your tires to Inches, so you can use more of these rearend calculators!
Speedometer Converter
When you buy bigger or smaller tires, your speed will change. Enter the diameters of your new and old tires, then enter a speed and see the difference!
Find MPH
Find out how fast your vehicle can move based on engine criteria, rearend ratios and tire size
Find RPM
Find out your engine's Revolutions Per Minute based on other engine criteria, tire size and rearend ratios
Find Overall Crawl Ratio
Figure out your off-road 4x4 crawl ratio based on transmission, axle and transfer case ratios