13. The expert from ETRTO proposed a correction to the 04 series of amendments to UN Regulation No. 117 (GRBP-82-27). GRBP adopted the proposal but agreed not to submit it immediately to WP.29 and AC.1, awaiting other amendment proposals to the same series of amendments.
16. The Co-Chairs of TF TA presented their proposals for a new UN Regulation on tyre abrasion, together with the corresponding amendments to UN Regulation No. 117 (ECE/TRANS/WP.29/GRBP/2025/27 as amended by GRBP-82-29 and ECE/TRANS/WP.29/GRBP/2025/28). GRBP noted that both ‘indoor drum’ and ‘on-road vehicle’ test methods were included on equal footing in the draft new UN Regulation, but a low level of correlation between the methods had been observed from the market assessment data, with much better results from the dedicated correlation-validation (COVA) testing campaign. GRBP also noted that the limit values for tyre abrasion remained to be determined for both Stages 1 and 2.
17. The expert of ETRTO highlighted the position of the EU tyre industry on setting the abrasion limits (GRBP-82-24, GRBP-82-25) and proposed modifications to the TF TA package of amendments (GRBP-82-37).
18. Several experts expressed the view that the drum method was not yet ready for adoption, given a low reproducibility of results in different laboratories and the need for further validation. They suggested to start first with the on-road method and add the drum method at a later stage. Some other experts were in favour of including both methods in the new Regulation from the beginning. Following an in-depth discussion on the methods and tyre abrasion limits, GRBP realized that it would not be possible to reach a consensus at this session and agreed to finalize the amendment package at the next meeting. GRBP invited experts from all Contracting Parties to actively participate in the coming TF-TA meetings to contribute to reaching a compromise at the next session.
19. The expert from India suggested to explicitly indicate that the draft new UN Regulation would apply to radial tyres only and not to bias-ply tyres.
21. The representative of ETRTO introduced ECE/TRANS/WP.29/GRBP/2026/6, as amended by GRBP-83-20-Rev.2. Concerns on transitional provisions, raised by the representative of Germany, were solved in GRBP-83-20-Rev.2. GRBP adopted the content of GRBP-83-20-Rev.2 and decided to leave it pending until all other proposals to amend the 04 series of amendments to UN Regulation No. 117 were discussed.
23. During the second part of the 83rd session of GRBP held on 17 March (see agenda item 5(g) below), the representative of ETRTO introduced GRBP-83-48-Rev.1, compiling all agreed proposals amending the 04 series of amendments to UN Regulation No. 117.
24. GRBP adopted GRBP-83-48-Rev.1 and requested the secretariat to submit it to WP.29 and AC.1 for consideration and vote at the June 2026 sessions as draft Supplement 4 to the 04 series of amendments to UN Regulation No. 117.