Proposal from the Worn Tyres working group to set the wet grip index threshold at 0.80 for class C1 tyres with a nominal aspect ratio equal to or less than 40, a section width equal to or higher than 235 mm and suitable for speeds equal to or greater than 300 km/h and for class C1 all terrain and special use tyres (see GRBP-75-27, slide 6). The proposal also introduces the k_worn factor in a new para. 3 in Annex 9 to address wet grip of C2 and C3 tyres in a worn state (see GRBP-75-26-Rev.1 for concept).

Proposal from the Worn Tyres working group to improve precision of the test procedures for measuring the wet adhesion of tyres in a worn state by using a moulded SRTT16 reference tyre (instead of a buffed tyre), to introduce new transitional provisions related to this change, to extend corrections already made to thee 02 series to the 03 series and make additional editorial corrections, and to define the range for tyre inflation vis-à-vis rim size to reduce uncertainties in measuring tread depth.

Proposal from the Studded Tyres task force to introduce provisions for C1 tyre ice-grip performance.

38. Based on GRBP-75-43-Rev.1, GRBP adopted a list of main decisions (Annex VI of the session report) in accordance with silence procedure.

15. GRBP recalled several proposals that had been briefly considered at the previous session (ECE/TRANS/WP.29/GRBP/72, para. 12). In view of a range of draft amendments to UN Regulation No. 138, GRBP agreed to start this work within a dedicated task force on quiet road transport vehicles (TF QRTV) which could later be transformed into an informal working group. The expert from OICA prepared draft Terms of Reference (GRBP-75-42) which received comments from the expert of China (GRBP-75-44). GRBP sought a Contracting Party who could take the lead of the task force, thanked OICA for having agreed to act as secretary and requested that the first meeting of the task force be convened in the coming months.

Proposal to avoid placing requirements in the Definitions section and to facilitate the text by making use of the definition of “service description” that was introduced by Supplement 24.

17. GRBP recalled that, at its previous session, it decided to continue consideration of ECE/TRANS/WP.29/GRBP/2021/13 in view of other draft amendments to UN Regulation No. 54 (ECE/TRANS/WP.29/GRBP/72, para. 16). The expert from ETRTO tabled a proposal that aimed to consolidate the calculation of reference dimensions with that provided in United Nations Global Technical Regulation (UN GTR) No. 16 (ECE/TRANS/WP.29/GRBP/2022/6).

18. GRBP adopted ECE/TRANS/WP.29/GRBP/2022/6 and ECE/TRANS/WP.29/GRBP/2021/13, as amended by GRBP-75-31-Rev.2, and requested the secretariat to submit it for consideration and vote at the June 2022 sessions of WP.29 and AC.1 as draft Supplement 25 to the original series of amendments to UN Regulation No. 54.

TF TA will address the tyres abrasion performance by determining a standardized measurement method which will allow for the quantification of the microplastic emissions in the environment. At the same time, the TF TA will investigate the correlation between abrasion rate and durability and consider the inclusion of both abrasion rate and durability

35. In cooperation with the Working Party on Pollution and Energy (GRPE), GRBP established a Task Force on Tyres’ Abrasion (TF TA) under the Co-Chairmanship of France and the European Commission, adopted its Terms of Reference (Annex IV, based on GRBP-75-39-Rev.1) and encouraged all experts to participate in the activities of TF TA. Many experts volunteered to contribute to the work of TF TA.