Considerations by TF-Data Analysis regarding tyre slopes, power train slopes, and part load model for the RD-ASEP Sound Expectation Model. Tyre slopes α = 40 and β = 20 are confirmed as appropriate for UN R117 approved tyres. Power train slopes are confirmed as well-framed to normal vehicle behaviour and consistent with Annex 7 ASEP Slope-Assessment principles. For part load model, the function is confirmed for ICE vehicles and HEV in ICE mode, while for EVs and HEVs in EV mode the part load area may require reworking, but the part load model should be applied uniformly to all vehicle techniques.

Progress Report (February 2026 – September 2026)
Conclusion of work on UN Regulation on tyre abrasion for C1 tyres, launch of C2 work, outlook for C3 work

Road legal race tyres are currently defined in the new UN R186 on abrasion but fall out of its scope. Considering that the new UN R186 on abrasion applies only to tyres that conform to UN Regulation No. 117., it is proposed to replicate therein the definition, the marking and the requirements of road legal race tyres by adding the new paragraphs 2.21., 4.5. and 6.9.

Proposal replaces the GRBP2026/26

Proposal to solve the discrepancies between the test report format and the description of the test method for C2 and C3 tyres.

The IWG for Wet Grip on Worn Tyres reports progress on evaluating methods for preparing tyres of Class C1 to be tested in worn state at type-approval, defining test conditions and methods, establishing type-approval thresholds for wet grip performance, and addressing requirements for classes C2 and C3. Test Campaign Stage 1 assesses test procedure precision per GRBP-80-11, with normal and 3PMSF tyres completely tested at 13 test centres. Outliers analysis and KPI target confirmation are ongoing. Stage 2, if needed, is planned for 2026-2027.

Draft agenda of the 76th session of the Informal Working Group WGWT scheduled for August 28th, 2026 on-line. The agenda includes welcome and opening remarks, adoption of the agenda, adoption of the minutes of the 75th session of 16 June 2026, review of work plan 2025-2026 for C1 tyres, review of IWG WGWT status report for GRBP 84th session of September 2026, and next meetings.

The Worn Tyres Post-Processing task force completed data collection for 3PMSF and Normal tyres, each with 57 samples representing 100% of target. Ongoing activities include outliers analysis of the 3PMSF and Normal cluster and post processing of the data conclusions.

Minutes of the 75th session of the Informal Working Group WGWT held 16 June 2026 on-line. The agenda was adopted. Previous meeting minutes from the 73rd session (31 March 2026) and 74th session (19 May 2026) were adopted. WTPP secretary updated on testing activities status per document WT-75-2. ETRTO stated the agreed number of tests was a statistical minimum and IWG WGWT conclusions to GRBP must be based on complete test results. IWG WGWT agreed to await WTPP conclusions on outliers before deciding whether to keep the current number of tests or make additional tests. The co-chair stated a status report must be prepared for GRBP 84th session (September 2026) and suggested an IWG WGWT meeting days before GRBP. Next IWG WGWT meeting scheduled for 28 August 9:00–10:00 CET.

Task Force Data Analysis held an online meeting on 7 July 2026. The group discussed database analysis, including insufficient data for higher performance and acceleration, and agreed that more data are needed. When new data are generated, operation conditions should focus on higher performances covering the ASEP range, higher accelerations up to and exceeding 5 m/s, pass-by runs with gear shifting, and low speed measurements in the UN R117 AVAS control range. The group reviewed proposals to the TF-Editing based on draft UN R51.04 and agreed some changes, with review results to be uploaded as Rev.1. A question regarding the phrase “but no more than 2.0 m/s” in paragraph 3.1.2.1.4.3 regarding vehicles with only one gear ratio was noted as issue #23 pending further review.

UN R117 establishes test procedures ensuring reliability, repeatability and reproducibility of results through standard reference test tyres manufactured by Manufacture Francaise des Pneumatiques Michelin in accordance with ASTM International standards. In 2024, the Russian Federation’s technical service was officially refused supply of these tyres due to export sanctions. The Russian Federation contends this refusal constitutes discrimination against a Contracting Party to the 1958 Geneva Agreement and calls on WP.29 to assess this discrimination and explain to the manufacturer its role in implementing the Agreement within the UN system.

Proposal to amend para. 2.18. to change the reference year from 24 to 26 for standard F2493, add new para. 2.21. defining “road legal race tyre,” add new para. 4.2.8. requiring the inscription “RLR” for road legal race tyres, insert new footnote 12 on marking height, renumber current footnote 12 to footnote 13 and amend its text, amend para. 5.4.1. to reference footnote 13, add new para. 6.9. establishing requirements for road legal race tyre classification, add new item 4.3. to Annex 1, amend para. 6.7. to change “classified” to “categorized,” amend Annex 3 para. 4.2.2. tables to change K1 unit from C to dB(A), amend Annex 3 Appendix 1 Part 2 item 3.1. to update ISO10844 reference from 2014 to 2021, and amend Annex 7 Appendix 3 Item 5 table to enable reporting of SRTT weighted average for each candidate.

Proposal to amend para. 2.18. to update the year reference in standard F2493 from 24 to 26, amend paras. 6.6. and 6.7. to change “classified” to “categorized”, revise tread depth and void to fill ratio requirements for class C1 special use tyres, restructure requirements for professional off-road tyres with subsections for each class, amend Annex 3 para. 4.2.2. to correct the measurement unit of coefficient K1 to dB(A), amend Annex 3 Appendix 1 Part 2 item 3.1. to update the ISO 10844 year reference from 2014 to 2021, and amend Annex 7 Appendix 3 Item 5 to enable SRTT weighted average to be reported for each candidate in the test results table.

WTPP has started post-processing activity for the 3PMSF cluster. 90% of test results for normal tyres are expected to be reached by June 2026. WTPP members are working on dataset correction including typos and rounding, and definition of the outliers.

The agenda includes discussion of the workplan 2025–2026 for C1 tyres and test campaign status, preparation of the IWG WGWT status report to GRBP 84th session (September 2026), and identification of next meetings scheduled for 2 July and 15 July 2026.

Task Force Data Analysis (Sub Group to IWG RD-ASEP) held its 13th meeting on Wednesday, 3rd June 2026. The group reviewed database analysis including statistical analysis of differences between expected and measured sound levels, sub-model construction, and optimization calculations for parameter tables. Discussion addressed model construction concerns, vehicle failure differentiation, and data collection requirements including approval values according to UN R117. Next meetings are scheduled for Tuesday, 7th July and Monday, 24th August 2026.

Draft minutes of the 74th session of the Informal Working Group WGWT held May 19th, 2026 (9:00–10:00 CET), remotely. Attendance per document WT-74-04. Agenda adopted. Previous meeting minutes of 73rd session (31 March 2026) not uploaded; to be adopted at next session per document WT-74-01. WTPP secretary updated on testing activities status per document WT-74-02. 3PMSF data from one test center pending before sharing anonymised data to WTPP for analysis. JASIC provided completed test data on 3PMSF and Normal tyres. Next meetings: WTPP 35 (28 May 09:00–10:30 CET); WTPP 36 (15 June 09:00–10:30 CET); 75th session (16 June 8:00–9:00 CET); WTPP 37 (02 July 09:00–10:30 CET); WTPP 38 (15 July 09:00–10:30 CET) per document WT-74-02.