11. The expert from the Netherlands recalled his earlier proposals on strengthening the tyre noise limits and reported on new developments in this field (GRB-68-27), including a proposal for the new European Regulation on General Safety. Finally, he sought consent of GRB for transforming GRB-66-03, which had proposed stricter noise limits, into a working document for the next session of GRB. The experts of Norway and CAETS generally supported the idea of reducing noise limits in UN Regulation No. 117. The expert of ETRTO recalled their comments presented at the previous session (GRB-67-08). The expert from EC pointed out that the proposal for the new European Regulation was still under discussion. For this reason, the Chair felt that it would be premature to submit an official document with the new tyres limits to the next session.

15. The expert from the Netherlands provided an overview of their research projects on tyres and proposed a two-stage tightening of the tyre limits for the rolling resistance coefficient, wet grip index and rolling sound emissions (GRB-66-01 and Add.1, GRB-66-03). He also highlighted the importance of keeping the correct tyre pressure for fuel efficiency and pointed out shortcomings of the EU system for labelling tyres.

16. The expert from ETRTO was of the view that the selections of tyres in the Dutch studies was not representative enough for the European market and volunteered to submit to the next GRB session a more comprehensive analysis. The expert from OICA supported the ETRTO view and proposal. He further introduced the results of a recent study of C1 summer tyres (GRB-66-22) according to which no tyre was performing equally well in rolling sound and handling. The expert from Germany acknowledged the progress achieved in rolling sound and pointed out the need to find a compromise for the three tyre parameters in question. He also agreed that the tyre labelling system would need to be improved.

17. The Chair was of the view that amending the limit values in Regulation No. 117 would first require a general agreement of all stakeholders, including the Working Party on Brakes and Running Gear (GRRF). Finally, GRB decided to continue the discussion at the next session.