This document specifies the method for measuring the relative wet grip braking performance index to a reference under loaded conditions for new tyres for use on commercial vehicles on a wet-paved surface. NOTE            The methods developed in this document are intended to reduce variability. A reference tyre is used to limit the variability of the testing method procedures. This document applies to all commercial vehicle, truck and bus tyres. This document does not apply to: —     tyres fitted with additional devices to improve traction properties (e.g. studded tyres); —     professional off-road tyres.