20. On behalf of the Informal Working Group on Wet Grip Performance of Tyres in Worn State (IWG WGWT), the expert from France reported on its progress (GRBP-77-30) and proposed to update its Terms of Reference (GRBP-77-03). GRBP decided to extend the mandate of IWG WGWT until February 2026 and adopted its revised Terms of Reference, as contained in annex II to the session report.

21. The expert of IWG WGWT proposed to add the missing references for the molded standard reference test tyre (SRTT16) in the 03 and 04 series of amendments to UN Regulation No. 117 (ECE/TRANS/WP.29/GRBP/2023/2 and ECE/TRANS/WP.29/GRBP/2023/3). GRBP endorsed these references and noted that they had been already included in ECE/TRANS/WP.29/2023/5 and ECE/TRANS/WP.29/2023/8 which would be considered by WP.29 and AC.1 at their forthcoming session in March 2023.

22. The expert from the European Commission proposed a new transitional provision (ECE/TRANS/WP.29/GRBP/2023/5). Following an in-depth discussion, GRBP adopted this proposal, as amended by GRBP-77-32, and requested the secretariat to submit it for consideration and vote at the June 2023 sessions of WP.29 and AC.1 as part of draft Supplement 1 to the 04 series of amendments to UN Regulation No. 117.

23. The expert from ETRTO proposed a correction (ECE/TRANS/WP.29/GRBP/2023/8). GRBP adopted the correction and requested the secretariat to submit it for consideration and vote at the June 2023 sessions of WP.29 and AC.1 as part of draft Supplement 1 to the 04 series of amendments to UN Regulation No. 117.

24. The expert from IWG MU proposed to update the rolling noise temperature correction for C1 tyres (GRBP-77-11 and GRBP-77-12). GRBP invited IWG MU to submit an official document for consideration at the next session.

25. The expert from the American Automotive Policy Council (AAPC) briefly introduced GRBP-77-23 and requested that time be allocated for discussion at the next session. He pointed out that several Middle Eastern countries outside the 1958 Agreement implement national and regional requirements based on UN Regulation No. 117. In the region, specialized pickup trucks are used in oil fields, mining, agriculture, forestry and other rough terrains for heavy tasks. According to the expert, for safety and durability reasons, these vehicles require suitable tyres where the vehicle mass and tyre combinations do not permit compliance with the rolling resistance limits of UN Regulation No. 117. GRBP invited GRBP experts to provide feedback and agreed to address this issue in detail at the next session.