16. GRBP received a status report of the Informal Working Group on Wet Grip Performance of Tyres in Worn State (IWG WGWT) (GRBP-81-23) and updated its Terms of Reference with the aim to define a Key Performance Indicator (KPI), to fix a target for the improvement of the test procedure precision and to extend the test campaign, if necessary (GRBP-81-22 and annex II).

17. The expert from ETRTO tabled editorial corrections to the 02 and 04 series of amendments to UN Regulation No. 117 (ECE/TRANS/WP.29/GRBP/2025/12 and ECE/TRANS/WP.29/GRBP/2025/13). GRBP adopted these proposals, as amended GRBP-81-08-Rev.1 and GRBP-81-09-Rev.1., and requested the secretariat to submit them for consideration and vote at the June 2025 sessions of WP.29 and AC.1 as respectively draft Supplement 17 to the 02 series of amendments and draft Supplement 3 to the 04 series of amendments to UN Regulation No. 117. For the latter, GRBP agreed to combine it with the amendment proposal to the same series of amendments that was adopted at the previous session (ECE/TRANS/WP.29/GRBP/2024/23 as amended by GRBP-80-11).

18. The Group of Interested Experts on UN Regulation No. 117 reported on their considerations on how to avoid further complexity of this Regulation created by new requirements, annexes and series of amendments with transitional provisions, due to the upcoming introduction of tyre abrasion requirements (GRBP-81-26). Among various options, the Group recommended to introduce abrasion performance in a separate UN Regulation. While several GRBP experts supported this idea, some others pointed out that this issue should be further considered at the EU level, because UN Regulation No. 117 was already indicated in EU decisions as the place holder of tyre abrasion provisions.

19. The expert from ETRTO briefed GRBP on reduction of measurement uncertainties in the rolling sound emission test method of UN Regulation No. 117 (GRBP-81-19). To advance on this topic, GRBP agreed to establish a dedicated group of interested experts (GOIE) on tyre noise level alignment.