Wheel & Tire Aspect Ratio Calculator

This Aspect Ratio Calculator gives the user a general but reasonable representation of alternative wheel/tire effects. Enter the Stock and Aftermarket tire designation, aspect and wheel size. This calculator works with MPH or KMH. Click on Calculate for the results. You may click on Clear to do another calculation.

U.S. DOT Tire Data Entry System**
Enter stock tire size
/ - R 		Enter aftermarket tire size
/ - R
Enter a reference speedometer value MPH or KMH
   
Calculated Aspect Ratio Results After Tire Changes
Stock tire width is inches. New tire width is inches.
Stock tire thickness is inches. New tire thickness is inches.
Stock tire diameter is inches. New tire diameter is inches.
When the vehicle speedometer indicates MPH or KMH
Actual vehicle speed is MPH or KMH

**Please be advised: The accuracy of this calculator and its applicability to your circumstances is not guaranteed. It's meant to be used as an informational guide only.  Always obtain professional advice from qualified automotive professionals if you have more questions about such issues.