25. GRBP was briefed on the activities of the IWG on Wet Grip Performance of Tyres in Worn State (IWG WGWT) (GRBP-80-34).

26. The expert of IWG WGWT proposed improving the precision of the test method for C1 tyres (ECE/TRANS/WP.29/GRBP/2024/23, GRBP-80-11 and GRBP-80-30). GRBP adopted the proposal, as amended by GRBP-80-11 and requested the secretariat to submit them for consideration and vote at the June 2025 sessions of WP.29 and AC.1 as draft Supplement 3 to the 04 series of amendments to UN Regulation No. 117. Should GRBP adopt another draft amendment to the same series of amendments at its session in February 2025, it would be combined with the above proposal.

27. The expert from ETRTO referred to their document with corrections to the 04 series of amendments to UN Regulation No. 117 (ECE/TRANS/WP.29/GRBP/2024/25) and requested to postpone its consideration, due to comments received from the experts of France, Netherlands and United Kingdom. GRBP agreed with this request and encouraged other experts to provide their comments as well.

28. The expert from AAPC recalled that, at the previous session, they had presented the proposal in ECE/TRANS/WP.29/GRBP/2024/17 that allowed, under certain conditions and weight limits, the use of LT-marked tyres with a rolling resistance greater than the current limits in UN Regulation No. 117. Following comments by the experts from France, Italy, Netherlands, Switzerland and United Kingdom, GRBP was not in a position to support the proposal and indicated that such exemptions should be granted at the national or regional levels. Taking into account the GRBP views, the expert from AAPC agreed to withdraw the document and to pursue the issue at the regional level.

29. The expert of ETRTO shared their concerns over the recent evolution of UN Regulation No. 117 which was becoming increasingly complex by regular additions of new requirements, annexes and series of amendments with transitional provisions (GRBP-80-25). To avoid further complexity with the upcoming introduction of tyre abrasion requirements, he proposed several options, including splitting the Regulation into several ones. To consider various options in detail, he argued for the establishment of a Group of Interested Experts (GOIE) with a task to develop a conceptual informal document for consideration and validation at the next session in February 2025, to be followed by a working document in September 2025. GRBP agreed with this proposal. Many experts volunteered to participate in GOIE.