ISO 23671:2021

This document specifies the method for measuring relative wet grip braking performance index to a reference under loaded conditions for new tyres for use on passenger cars on a wet-paved surface.
The methods developed are meant to reduce variability. The use of a reference tyre is necessary to limit the variability of the testing procedures.
This document applies to all passenger car tyres except for:
—    special-use tyres marked with "ET";
—    T-type temporary spare tyres;
—    tyres fitted with additional devices to improve traction properties (e.g. studded tyres).