15. The expert from ETRTO assessed the latest proposals from the Netherlands for stricter tyre noise limits, as presented at the sixty-sixth session of GRB (GRB-67-08). He pointed out some limitations in the data subset used in the Dutch study and questioned the methodology used to derive the new proposed limits from the data subset. The expert from the Netherlands replied to the ETRTO comments (GRB-67-18).

16. The experts from Germany and OICA pointed out that the Dutch study had been based on tyre labels which might be incorrect. The expert from the Russian Federation drew the attention of GRB to the need for a holistic approach to the tyre rolling noise in the system “tyre/road surface”. The Chair noted two different approaches for tyre selection by the Netherlands and ETRTO: the Dutch study focused on the most popular tyres of several brands covering about 90 per cent of the market, while ETRTO was concerned about a much wider selection of brands to ensure market choice.

17. GRB invited the Netherlands, ETRTO and other stakeholders to work together with the aim to undertake a holistic study of tyres on the market. Finally, GRB agreed to resume the discussion at 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.

12. The expert from the Netherlands presented a study (GRB-62-09 and Add.1) on noise emission from the Original Equipment Manufacturer (OEM) tyres of a specific size which were found to be around 1 dB(A) lower than the one from replacement tyres of the same size. The expert, thus, proposed to further reduce the limit values for OEM tyres in the 02 series of amendments to Regulation No. 117 (GRB-62-11 and Add.1).

13. The expert from Switzerland expressed his support for the general direction of the Dutch proposal. The experts from Germany and EC were of the view that, at this stage, it would be premature to tighten the tyre noise limits of Regulation No. 117. The expert from France called for a holistic approach to this issue. The experts from ETRTO and OICA expressed doubts about the representativeness of the tyre sample used in the Dutch study. The expert from ETRTO also delivered comments on the proposal for amendments to Regulation No. 117 (GRB-62-17). Finally, GRB invited all experts to further study the Dutch proposal and decided to revert to this issue at the next session.