1. The Working Party on Noise and Tyres (GRBP) held its seventy-third virtual session from 26 to 29 January 2021 in Geneva.1 The meeting was chaired by Mr. S. Ficheux (France). Experts from the following countries participated in the work following Rule 1(a) of the Rules of Procedure of the World Forum for Harmonization of Vehicle Regulations (WP.29) (TRANS/WP.29/690/Rev.1): Canada, China, Czech Republic, Finland, France, Germany, Hungary, India, Italy, Japan, Netherlands, Norway, Republic of Korea, Russian Federation, Spain, Sweden, Switzerland, United Kingdom of Great Britain and Northern Ireland and United States of America. An expert from the European Commission (EC) participated. Experts from the following non-governmental organizations also participated: Bureau International Permanent des Associations de Vendeurs et Rechapeurs de pneumatiques (BIPAVER), International Motor Vehicle Inspection Committee (CITA), European Association of Automotive Suppliers (CLEPA), European Garage Equipment Association (EGEA), European Tyre and Rim Technical Organization (ETRTO), Motorcycle Manufacturers Association (IMMA), International Organization for Standardization (ISO), Imported Tyre Manufacturers Association (ITMA) and International Organization of Motor Vehicle Manufacturers (OICA).

2. GRBP considered and adopted the agenda (ECE/TRANS/WP.29/GRBP/2021/1, as amended by GRBP-73-01). GRBP noted the running order proposed by the Chair (GRBP-73-06). The list of informal documents is contained in Annex I to the session report. The list of GRBP informal groups is reproduced in Annex V.

GRBP-73-01 | GRB-73: Updates to the provisional agenda

GRBP-73-06/Rev.1 | Running order of the 73rd (January 2021) GRBP session

GRBP/2021/1 | GRBP: Annotated provisional agenda for the 73rd (January 2021) session

3. The expert from IMMA proposed to correct references in the recent series of amendments (GRBP-73-04). GRBP adopted the proposal and requested the secretariat to submit it for consideration and vote at the June 2021 sessions of WP.29 and AC.1 as a draft Supplement to the 04 and 05 series of amendments to UN Regulation No. 41.

GRBP-73-04 | UN R41: Proposal for amendments to the 04 series of amendments Proposal to correct some references, which need to be updated as a consequence of document WP.29/2020/70, adopted at the June 2020 WP.29 session, notably<ol class="alpha"><li>Paragraph 5.4.1 renumbered as paragraph 5.5.1.</li><li>Paragraphs 5.4. and 5.5. respectively renumbered as paragraphs 5.5. and 5.6.</li></ol>

4. The expert from EC briefed GRBP on an ongoing study of the impact assessment of Euro 5 sound emissions level limits for L-category vehicles (GRBP-73-26). Several experts invited him to keep GRBP informed of the study progress.

GRBP-73-26 | Technical support for the impact assessment on Euro 5 step of L-category sound emissions level limits

5. The experts from EC, ETRTO and OICA reported on their studies on sound level limits (GRBP-73-23, GRBP-73-11 and GRBP-73-25, respectively). To coordinate such initiatives, GRBP decided to establish a taskforce (TF) and sought a volunteer among the experts from Contracting Parties to take the leadership of TF, while OICA agreed to act as secretary. GRBP considered that TF should address the sound level limits of UN Regulation No. 51 and, at a later stage, No. 41. To kick-off the TF activities without delay, the Chair pointed out that he could take the lead of TF on a temporary basis, if needed.

GRBP-73-11 | ETRTO Tyre Performance Study Overview of UTAC CERAM testing designed to consider the impact of additional tightening of tyre performance limits on the balance between legal requirements (rolling resistance, wet grip and rolling sound emission) and other performance aspects not subject to legal requirements.

GRBP-73-23 | Study on sound level limits of M- and N-category vehicles

GRBP-73-25 | Study on future sound-limit values

6. On behalf of the Informal Working Group on Additional Sound Emission Provisions (IWG ASEP), the expert from Germany introduced a draft new 04 series of amendments to UN Regulation No. 51 (GRBP-73-05). GRBP noted that a revised proposal would be submitted to the next session.

GRBP-73-05 | UN R51: Proposal for 04 series of amendments Proposal by experts from IWG ASEP for new series of amendments.

7. The expert from Norway, in his capacity of Chair of the Informal Working Group on Measurement Uncertainties (IWG MU), reported on the progress of IWG MU (GRBP-73-14-Rev.1) and proposed to update its Terms of Reference (GRBP-73-16). GRBP adopted the revised Terms of Reference, as laid down in Annex II of the session report.

GRBP-73-14/Rev.1 | Status report of the Sound Measurement Uncertainties informal working group

GRBP-73-16 | Revised terms of reference for the Sound Measurement Uncertainties informal group

8. The experts from IWG MU also presented a draft reference document with a general approach to estimate measurement uncertainties (GRBP-73-15) and draft amendments to the 03 series of amendments to UN Regulation No. 51 (GRBP-73-17).

GRBP-73-15 | General Approach to Estimate Sound Measurement Uncertainties

GRBP-73-17 | UN R51: Proposal to amend the 03 series of amendments Measurement Uncertainties informal group proposal to clarify the text and to amend:<ol class="alpha"><li>Annex 3, Paragraph 1.4. to delete determination of the vehicle speed by independent speed measuring devices</li><li>Annex 3, Paragraph 1.5. to clarify that no determination of the wind speed is needed for indoor testing</li><li>Annex 3, Paragraph 2.1.3. to clarify and differentiate between indoor and outdoor testing</li><li>Annex 3, Paragraph 2.1.3.1.2. to clarify the temperature range for indoor facilities.</li><li>Annex 3, Paragraph 2.1.3.2.2. to clarify the temperature range for outdoor facilities.</li></ol>

9. The Chair recalled the extension of the mandate of IWG on Quiet Road Transport Vehicles (QRTV) for the Global Technical Regulation (GTR) until December 2021 and invited the expert from the United States of America, being Chair of IWG QRTV GTR, to report on their progress at the next session of GRBP in September 2021.

10. The expert from ETRTO introduced ECE/TRANS/WP.29/GRBP/2021/4. GRBP adopted the proposal and requested the secretariat to submit it for consideration and vote at the June 2021 sessions of WP.29 and AC.1 as a draft Supplement to the 02 series of amendments to UN Regulation No. 30.

GRBP/2021/4 | UN R30: Proposal for a new Supplement to the 02 series of amendments Proposal to amend the extended mobility tyre (EMT) symbol following the detection of dimensional inconsistencies within the International Organization for Standardization Working Group (ISO) TC31/SC3/WG19, where the dimension "0,33h" was judged wrong and constituting an unnecessary over constraint and to amend the inflation value to be used for the tyre conditioning when assessing the "flat tyre running mode" of "run flat tyres" and of "extended mobility tyres".

11. The expert from France proposed a new definition for the radial structure (GRBP-73-20-Rev.1). The expert from ETRTO made a study reservation. GRBP invited the expert from France to prepare, in cooperation with ETRTO, a new working document for the next session.

GRBP-73-20/Rev.1 | UN R30: New radial tyre structure definition proposal

12. GRBP noted that the experts of BIPAVER had withdrawn document ECE/TRANS/WP.29/GRBP/2021/2.

GRBP/2021/2 | UN R108: Proposal for amendments Proposal to align the provisions for retreaded tyres with the proposals of France for UN Regulation No. 30 and of the European Tyre and Rim Technical Organization (ETRTO) for UN Regulation No. 117.

13. GRBP noted that the experts of BIPAVER had withdrawn ECE/TRANS/WP.29/GRBP/2021/3.

GRBP/2021/3 | UN R109: Proposal for amendments Proposal to align the provisions for retreaded tyres with the proposals of the European Tyre and Rim Technical Organization (ETRTO) for UN Regulations Nos. 54 and 117.

14. The expert from France proposed to update and revise the text of UN Regulation No. 109 (GRBP-73-21). The experts from the Netherlands and BIPAVER commented on the proposal. GRBP invited the experts from France, Netherlands and BIPAVER to cooperate with the aim to prepare a working document for the next session.

GRBP-73-21 | UN R109: Proposal for Supplement 11 Proposal to clarify:<ol class="alpha"><li>Signature of the 3PMSF test reports</li><li>Mould cure retreaded tyre (not UN R117 pattern).</li></ol>

15. On behalf of IWG for Wet Grip on Worn Tyres (WGWT), the expert of France reported on their progress (GRBP-73-18).

GRBP-73-18 | Status report of the Worn Tyres working group

16. The expert from EC proposed to include C2 and C3 tyres in the Terms of Reference of IWG WGWT (GRBP-73-02). The expert from ETRTO presented a preliminary assessment of wet grip on worn C2 and C3 tyres (GRBP-73-22) and suggested further modifications to the Terms of Reference (GRBP-73-08). Based on a consolidated proposal in GRBP-73-27-Rev.1, GRBP adopted revised Terms of Reference of IWG WGWT as laid down in Annex III to the session report.

GRBP-72-02 | Worn tyres: Proposal for working group terms of reference

GRBP-73-08 | Proposal to amend the Worn Tyres working group terms of reference Proposal to include requirements for wet grip of tyres of classes C2 and C3 in worn state to the scope of the working group activities.

GRBP-73-22 | Tyre industry preliminary assessment of wet grip on worn C2 and C3 tyres

GRBP-73-27/Rev.1 | Working group on Worn Tyres: Proposal for revised terms of reference

17. The expert from ETRTO proposed to introduce in UN Regulation No.117 a definition of “ice tyre” for C1 tyres (GRBP-73-19). The Chair invited ETRTO to submit a working document for consideration at the next session.

GRBP-73-19 | UN R117: Proposal to introduce an Ice Tyre definition for C1 class tyres

18. The expert from Germany proposed amendments with a view to adapting UN Regulation No. 124 to the current requirements for type approvals (ECE/TRANS/WP.29/GRBP/2021/7). GRBP adopted this proposal and requested the secretariat to submit it for consideration and vote at the June 2021 sessions of WP.29 and AC.1 as a new Supplement to UN Regulation No. 124 .

GRBP/2021/7 | UN R124: Proposal for amendments Proposal to require wheel attachments with three or more fixing components (nuts or studs) in the scope of the Regulation, to restrict the difference in pitch circle diameter (PCD) of a wheel type comprised of more than two versions, to carry out additional rotating bending tests on each version with a PCD difference to a tested version of more than 6.5 mm, and to establish specifications for comparison of replica wheels with the minimum level of the vehicle manufacturer´s replacement wheels.

19. GRBP took note of the activities of the Task Force on Tyre Pressure Monitoring System and on Tyre Installation (TF TPMSTI) (GRBP-73-13) and addressed amendment proposals on the requirements for the communication interface between the towing and towed vehicles that had been prepared by TF TPMSTI (ECE/TRANS/WP.29/GRBP/2021/6 and GRBP-73-03).

20. GRBP adopted the proposals and requested the secretariat to include them in a revised document ECE/TRANS/WP.29/2021/10/Rev.1 for consideration and vote at the March 2021 sessions of WP.29 and AC.1 as part of a draft new 01 series of amendments to UN Regulation No. 141.

GRBP-73-03 | UN R141: Proposal to amend the 01 series of amendments Proposal from the TPMSTI task force to revise the communication interface protocol of TPMS between towing and towed vehicles of categories N2, N3 and O3, O4, respectively (described in Annex 5 on the basis of the ISO bus requirements) in alignment with UN R13 and ISO updates. The proposal further corrects and clarifies provisions across TPMS, TPRS and CTIS.

GRBP-73-13 | Status report of the TPM and Tyre Installation task force

GRBP/2021/6 | UN R141: Proposal for Supplement 1 to the 01 series of amendments Proposal prepared by the experts on communication interfaces of the Task Force on Tyre Pressure Monitoring System and Tyre Installation (TF TPMSTI) to update the requirements on the communication interfaces between towing and towed vehicles.

WP.29/2021/10/Rev.1 | UN R141: Revised proposal for the 01 series of amendments Text prepared by the experts of TF TPMSTI in order to align with the provisions of European Union Regulation 2019/2144 and to introduce the TPMS requirements for all vehicle categories, including trailers. The proposal addresses the communication interface protocol of TPMS between towing and towed vehicles of categories N2, N3 and O3, O4, respectively (described in Annex 5 on the basis of the ISO bus requirements) in alignment with UN R13 and ISO updates. The proposal further corrects and clarifies provisions across TPMS, TPRS and CTIS.

21. The expert from Finland reported on the progress of the Task Force on Studded Tyres (TF ST) (GRBP-73-07) and introduced a proposal for a new UN Regulation which had been prepared by TF ST (ECE/TRANS/WP.29/GRBP/2021/5). GRBP agreed to revert to the document at the next session, thus giving GRBP experts an opportunity to further study the document and to provide comments.

GRBP-73-07 | Status report of the task force on Studded Tyres

GRBP/2021/5 | Studded tyres: Proposal for a draft new UN Regulation Proposal prepared by the Task Force on Studded Tyres (TF ST) to establish a new UN Regulation on uniform provisions concerning the approval of studded tyres with regard to their snow performance (distinguished from studdable tyres regulated by UN Regulation No. 117).

22. On behalf of the Task Force on Reverse Warning (TF RW), the expert from Japan reported on the progress of TF RW (GRBP-73-12). GRBP noted that a proposal for a new draft UN Regulation on reversing alarm would be submitted to the next session. Meanwhile, GRBP encouraged all experts to consider GRBP-73-12 and to provide comments to TF RW, in particular on the proposed sound level limits.

GRBP-73-12 | Status report of the Reversing Warning Sounds task force

23. GRBP recalled the studies which were introduced under agenda items 2 and 3.

GRBP-73-23 | Study on sound level limits of M- and N-category vehicles

GRBP-73-26 | Technical support for the impact assessment on Euro 5 step of L-category sound emissions level limits

24. No issues were considered under this item.

25. No new information was provided.

26. GRBP took note of the highlights of the November 2020 session of WP.29 on GRBP and common issues (GRBP-73-10). In particular, GRBP was informed that WP.29 had revised a transitional provision on the possibility of granting type approvals according to the preceding series of amendments to a UN Regulation (WP.29-182-11).

GRBP-73-10 | General information and WP.29 highlights relevant to GRBP activities

WP.29-182-11 | Proposal for amendments to ECE/TRANS/WP.29/1044/Rev.2 (Guidelines on transitional provisions) Proposal from the informal working group on the International Whole Vehicle Type Approval (IWVTA) system.

27. GRBP noted a revised list of the GRBP priorities (GRBP-73-24) and that the Chair would convene in February 2021 an informal meeting on this issue as well as on the leadership of TF on noise limits.

GRBP-71-13/Rev.3 | 2020 schedule of meetings of interest to GRBP experts

GRBP-73-24 | Priorities of the Working Party on Noise and Tyres (GRBP)

28. The expert from France presented an updated schedule of meetings that were of interest to GRBP experts (GRBP-71-13-Rev.5).

GRBP-71-13/Rev.5 | GRBP Meeting Schedule, Holidays & Milestones

29. GRBP noted a mistake in the French text of UN Regulation No. 75 (GRBP-73-09) and requested the secretariat to liaise with the UN services to have it corrected.

GRBP-73-09 | UN R75: Proposal for a corrigendum to the French version of the text

30. Based on GRBP-73-28-Rev.1, GRBP adopted a list of main decisions (Annex IV of the session report) in accordance with silence procedure.

GRBP/28/Rev.1 | Draft list of main decisions during the 73rd (January 2021) GRBP session

31. For its seventy-fourth session, scheduled to be held in Geneva from 15 to 17 September 2021, GRBP decided to keep the same structure for the provisional agenda. GRBP noted that the deadline for the submission of official documents to the secretariat would be 28 June 2021, twelve weeks prior to the session.