14. GRB continued its consideration of the revised proposal for new time measurement accuracy for the rolling resistance method (ECE/TRANS/WP.29/GRB/2014/8). The expert from Japan introduced several modifications to this proposal (GRB-61-06). GRB adopted the proposal, as contained in Annex V to this report, and mandated the secretariat to submit it to WP.29 and AC.1 for consideration and vote at their June 2015 sessions as a draft Supplement 8 to the 02 series of amendments to Regulation No. 117. GRB also noted that the Working Party on Brakes and Running Gear (GRRF), at its February 2015 session, would consider a corrigendum to Supplement 6 to the 02 series of amendments to Regulation No. 117 (ECE/TRANS/WP.29/GRRF/2015/9).

15. The expert from France presented the results of testing tyres of commercial vehicles (classes C2 and C3) for the deceleration test method using the dω/dt form for measuring rolling resistance (GRB-61-09). The aim of this study was to compare the measurements obtained at a dedicated and non-dedicated rolling resistance machine. The results at the non-dedicated rolling resistance machine demonstrated a poor repeatability of the measurements, thus leaving open the question whether or not such machines are suitable for the proposed deceleration test method. GRB was of the view that further studies would be necessary and encouraged other laboratories to conduct such tests.

16. The expert from ETRTO referred to the ongoing work of updating references to the new version of ISO standard 10844:2014 (see para. 17 below) and proposed similar amendments to Annex 3 of Regulation No. 117 (GRB-61-14). The expert of ISO recalled his presentation on the comparison between the 2014 and 2011 versions of ISO 10844 (GRB-60-17) and confirmed that only editorial modifications had been introduced without any technical changes. Thus, GRB agreed that no transitional provisions were required in this case. GRB adopted the proposal, as contained in Annex VI to this report, and mandated the secretariat to submit it to WP.29 and AC.1 for consideration and vote at their June 2015 sessions as a draft supplement to Regulation No. 117.