Division 5.2.1.1

The noise test of the silencing system and the replacement silencing system has to be executed with the same normal tyres, as defined in paragraph 2 of UNECE Regulation No 117. At the request of the manufacturer, the tests shall not be done with traction tyres, special use tyres or snow tyres, as defined in paragraph 2 of UNECE Regulation No 117. Such tyres could increase the sound level of the vehicle or would have a masking effect on the noise reduction performance comparison. The tyres may be of used condition but shall satisfy legal requirements for in-traffic use.