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.

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.

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.

The 73rd session of the Informal Working Group on Wet Grip of Worn Tyres convened remotely on 31 March 2026. The agenda and previous session minutes from 3 February 2026 were adopted. The WTPP secretary reported on testing activities status for the workplan stage 1 for C₁ tyres, with results to be presented to GRBP at its 84th session in September 2026. ETRTO stated conclusions can only be made on complete datasets. Future meetings are scheduled through July 2026.

The Worn Tyres Post-Processing task force held its 34th session on 13 May 2026. Ninety-three percent of 3PMSF tests have been completed and members agreed to start the post-processing activity for the 3PMSF cluster. Test results for Normal tyres will be delivered once the high temperature range will be achieved. Future sessions are scheduled for 28 May, 15 June, 2 July, and 15 July 2026.

The agenda for the 74th session of the Informal Working Group on Wet Grip of Worn Tyres scheduled for May 19th, 2026, remotely via Teams. The agenda includes welcome and opening remarks, adoption of the agenda and minutes of the previous 73rd session meeting held 31 March 2026, discussion of the workplan 2025 for C1 tyres status test campaign, and determination of the next meeting date.

Proposal to amend para. 2.18. to update Standard Reference Test Tyre definitions with ASTM International standards E1136 19, F2493 24, F2872 25, F2871 25, F2870 23, F3678 25, and F3677 23 for specified tyre sizes and designations, and amend para. 12.21. to permit Contracting Parties to continue accepting existing type approval and extensions to existing type approvals of class C3 tyres first granted before 1 September 2028 using SRTT19.5 or SRTT22.5, with SRTT19.5 siped or SRTT22.5 siped required for new tests performed on different representative tyre sizes for extensions granted after 01 September 2028.

Proposal to delete Table of contents, Annex 10 and all its appendices, amend para. 1.1. to clarify application to new pneumatic tyres of classes C1, C2 and C3 in new state regarding sound emissions and rolling resistance and in new and worn state regarding wet adhesion, delete para. 1.3., amend para. 2.18. to specify reference tyres F2872-25, F2871-25, F3678-25 and F3677-23, delete para. 2.21., delete para. 3.1.1.1., amend para. 3.2.1. to describe major features and their effects on tyre performance, delete paras. 5.7. to 5.10., delete Annex 1 items 8.6. and 8.6.1., amend Annex 5 part (b) para. 1.1.1. to establish surface friction values by trailer or vehicle method according to tyre class and SRTT, amend Annex 5 part (b) para. 1.1.1.1. regarding coefficient of variation and peak braking force coefficient, and delete Annex 10. Document based on GRBP/2025/28, GRBP-82-27, GRBP/2026/6, GRBP-83-20-Rev.2 and GRBP-83-48-Rev.1.

Proposal to amend Annex 5, part (B) of UN R117. Changes include replacing “Average Deceleration (AD)” with “braking force coefficient (BFC)” terminology throughout paragraphs 2.2.2.1., 2.2.2.7.1., 2.2.2.7.2., and 2.2.2.7.3. Paragraph 2.2.2.3. is amended to clarify terminology regarding vertical static test load and load capacity. Paragraph 2.2.2.7.4. is deleted. Paragraphs 2.2.2.7.5. through 2.2.2.8.4. are renumbered and amended to align the wet grip test method for C2 and C3 tyres with changes made to the passenger car test method and ISO 15222:2025.

Proposal to supersede GRBP/2025/28, consolidating amendment proposals from GRBP/2025/28, GRBP-82-27, GRBP/2026/6, and GRBP-83-20-Rev.2. Changes include moving tyre abrasion provisions to a separate UN Regulation, deleting paragraphs 5.7 to 5.10 and Annex 10, updating ASTM standard references to F2872-25, F2871-25, and F3678-25, amending Annex 5 part (b) paragraph 1.1.1., and deleting paragraph 2.21. defining abrasion performance terms.

ETRTO measurement uncertainties reduction efforts for UN R117 rolling sound emission test methods are progressing through outdoor and indoor Round Robin tests. Eight of thirteen outdoor test centres have completed tests for C₁ and C₂ tyres; remaining centres anticipate completion by mid-year. Indoors, two of six ETRTO test centres completed tests with others expected finished by mid-year. An intermediate report with available data will be presented in September 2026, full results postponed to February 2027, and the Working Document with test method evolution now expected in September 2027 instead of February 2027.

Proposal to amend paragraph 2.18. to update Standard Reference Test Tyre definitions to ASTM International standards: E1136-19 for SRTT14, F2493-24 for SRTT16, F2872-25 for SRTT16C, F2871-25 for SRTT19.5, F2870-23 for SRTT22.5, F3678-25 for SRTT19.5 siped, and F3677-23 for SRTT22.5 siped. Also amend paragraph 12.21. to accept existing type approvals and grant extensions to class C₃ tyres using either SRTT19.5 or SRTT22.5 before 1 September 2028, and use SRTT19.5 siped or SRTT22.

The GOIE on Tyre Noise Level Alignment in UN R117 targets reducing dispersion of measurements for tyres of Class C1 and C2 and investigating possibility to develop a test method with an SRTT as reference. An intermediate report will be presented to GRBP in September 2026, with a Working Document proposing evolution of the test method by September 2027. Five meetings have been held with 13 test centres from France, Japan, Netherlands, Spain and ETRTO. Eight of thirteen test centres have completed tests on 15 C1 and 5 C2 Japanese market tyres, with completion targeted for mid-2026.

The secretary reported on C1 tyre testing activities. The Netherlands and Germany noted potential delays in Normal tyre testing at high temperature by end of March due to temperature conditions. The co-chair presented a status report for GRBP’s 83rd session, which the group approved. Future meetings are scheduled for February through April.

Proposal to update references the latest international standard specifications ASTM
F2872-25, F2871-25 and F3678-25.

Addresses a real-life situation that is not considered by current ice grip test conditions: the wet ice (or black ice) conditions.

Proposal for new provisions for the track characterization with additional new text and re-introduces deleted text

Proposal to replace ECE/TRANS/WP.29/GRBP/2024/8, applies also to UN R117

Proposal from the GRBP task force on Tyre Abrasion to delete provisions from UN R117 that are covered by the proposal for a new UN Regulation on tyre abrasion.

Proposal to clarify tyre abrasion provisions, including to add an ice temperature range of -5°C to -2°C to the test conditions for ice grip tyres.

Proposal to standardize provisions for the water depth measurement, reduce the track friction range requirements under the test procedures, clarfy that adhesion performance on wet surfaces (wet adhesion) is required not only for C1 tyres, but also C2 and C3 tyres, update the standards references to ASTM F2493-244, F3611-24, F3676-24, F3675-24 and ISO 4000-1:2024, align the definitions of tread groove and principal grooves with proposals for UN R30 and R54, simplify the wording of the requirements for professional off-road tyres, and correct the transitional provision in paragraph 12.23. to specify approvals “first issued after 31 August 2028”.

Proposal to

1. Update standard reference to ASTM F2493-24 and ISO 4000-1:2024
2. Align the definitions of tread groove and principal grooves with proposals for UN R30 and R54
3. Simplify the wording of the requirements for professional off-road tyres
4. Correct the transitional provision in paragraph 12.23. to specify approvals “first issued after 31 August 2028”.

Proposal to

1. Update standard reference to ASTM F2493-24 and ISO 4000-1:2024
2. Align the definitions of tread groove and principal grooves with proposals for UN R30 and R54
3. Simplify the wording of the requirements for professional off-road tyres
4. Correct the transitional provision in paragraph 12.23. to specify approvals “first issued after 31 August 2028”.

Proposal to

1. Clarfy the scope to reflect that adhesion performance on wet surfaces (wet adhesion) is required not only for C1 tyres, but also C2 and C3 tyres
2. Update standard reference to ASTM F2493-244, F3611-24, F3676-24, F3675-24 and ISO 4000-1:2024
3. Align the definitions of tread groove and principal grooves with proposals for UN R30 and R54
4. Simplify the wording of the requirements for professional off-road tyres
5. Correct the transitional provision in paragraph 12.23. to specify approvals “first issued after 31 August 2028”.

Presentation by the IWG WGWT on the proposal to replace document ECE/TRANS/WP.29/GRBP/2024/23 by GRBP-80-11

ETRTO recommends to create a GRBP GOIE (Group of Interested Experts) involving CP’s
and NGO’s and with the goal to present an Informal Document by GRBP February 2025
session to validate the concept to be followed and implemented in a Working Document
by September 2025

Proposal by the IWG WGWT to replace document ECE/TRANS/WP.29/GRBP/2024/23. This proposal aims as a first step to standardize the water depth measurement.

Draft proposal to supersede the proposal in document GBRP/2024/23 (concerning water-depth measurement provisions and track-friction range requirements).

Proposal from the Wet Grip on Worn Tyres informal group to standardize provisions for the water depth measurement and to reduce the track friction range requirements under the test procedures.

Proposal to clarify that wet adhesion provisions apply to C1, C2, and C3 tyres, correct ISO and internal references, clarify symbols “ARC” and “ARR” relationships to indoor drum test method, and clarify application to M+S marked tyres.

Working draft proposal concerning wet grip performance of worn tyres.

Proposal to improve the reproducibility of the snow grip test method by replacing the current reference tyres C3 SRTTs 19.5 and 22.5 with the new reference tyres C3 SRTTs 19.5 and 22.5 siped, to make editorial improvements and updates to ISO and ASTM standards references, and to align with Supplement 2 to the 04 series of amendments, including a new temperature correction formula for the rolling sound emissions of tyres of classes C1 and C2 and to remove the content of the now obsolete Annex 4 as well as all its references.

Proposal to introduce a new temperature correction formula for the rolling sound emissions of tyres of classes C1 and C2, to remove the content of the now obsolete Annex 4 as well as all its references, to update references to standards, to improve the reproducibility of the snow grip test method by replacing the current reference tyres C3 SRTTs 19.5 and 22.5 with the new reference tyres C3 SRTTs 19.5 and 22.5 siped, and to make editorial improvements for clarity and consistency across tyre regulations.

Proposal to introduce measures to reduce variability in noise measurements and new test methods to measure tyre abrasion.

Amendments from the Task Force on Tyre Abrasion (TFTA) to the proposal to introduce test methods to measure tyre abrasion.

Proposal to replace document ECE/TRANS/WP.29/GRBP/2024/06

Proposal to replace document ECE/TRANS/WP.29/GRBP/2024/09

Proposal to replace document ECE/TRANS/WP.29/GRBP/2024/07