Tire Size, Speedometer Error Calculator
By Isaac DeCoursey @ EverythingCelica.com

Online Wheel Speed Calibration calculator is at https://celicahobby.com/tech/speedcalc.html

This calculator is for comparing original equipment tire size to alternate after market tire sizes. All calculations are round up. Calculations are to be treated as approximate only, due to variations in how tires are manufactured.

The following is an example to help to decode a tire size like P195/60 R15
195 = tire width in millimeters, measured from sidewall to sidewall
60 = sidewall ratio, the ratio of sidewall height to tire width
15 = wheel rim diameter in inches


Factory stock Celica GT tires:
P195/60 R15 on steel rims

Factory stock Celica GTS tires:
P205/55 R15 on aluminum alloy rims
or
P205/50 R16 on aluminum alloy rims

What I currently have installed on my Toyota Celica:
Kumho 712 tires (225/40 ZR18) on Exel DL46 Gunmetal 18" rims
Exel DL46 Tire Size.jpg