Car tyre size calculator
Calculate tyre size
Type the car tyre code you want to calculate in the text box, to see the results below. Type your code as it is written on your tyre, for example 195/70R15 (ISO metric tyre code) or 195/620R16 (Japanese tyre code).
The ISO metric equivalent of
Nominal width of tire in mm Height of sidewall in % of width R=radial Rim diameter code
Your tyre dimensions, metric:
Width, mm
Height of sidewall, % of width
Height of sidewall, mm
Fits rim diameter, mm
Tyre diameter, mm
Rolling circumference, mm*
Tyre circumference, mm
Rolling radius, mm
Wheel radius, mm
Revoluions per km
Your tyre dimensions, British/American:
Width, in
Height of sidewall, % of width
Height of sidewall, in
Fits rim diameter, in
Tyre diameter, in
Rolling circumference, in*
Tyre circumference, in
Rolling radius, in
Wheel radius, in
Revolutions per mile
* To calculate rolling circumference Convertworld uses the tyre dimensions at a factor of 0.96 to simulate the slight reduction of radius which occurs when a tyre is fitted to a car and meets the ground.
