Equivalent sizes

Step 1: Determine the corresponding SRI using the original dimension.

SRI: " Speed Radius Index" is a parameter used to calculate the theoretical speed of vehicles during EU certifi cation procedures and for the interchangeability of tyre dimensions.

Step 2: Based on the SRI result from step 1, determine the possible dimensional equivalences.

This equivalence chart has been produced using ETRTO data; it is not exhaustive. Please consult us for other conversions.

Determine the possible dimensional
Determine the possible dimensional


  • In no case does the SRI correspond to a specific value of the circumference of the bearing. It is only given for information purposes only. It is necessary to verify via measurements.
  • Any transformation requires the ratio between the bridge and the rate of preponderance to be calculated in order to check that the width and diameter of the rims are compatible.