本文件规定了在湿铺路面上商用车辆上使用的新轮胎在负载条件下的相对湿抓地力制动性能指数的测量方法。 本文件中制定的方法旨在减少可变性。有必要使用参考轮胎，以限制试验方法程序的可变性。 本文件适用于所有商用车、卡车和公共汽车轮胎。 本文件不适用于: -？装有附加装置以提高牵引性能的轮胎（例如，钉胎）； -？专业越野轮胎。

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 commercial vehicles on a wet-paved surface. The methods developed in this document are meant to reduce the variability. The use of a reference tyre is necessary 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.