Proposal to address the definition of the radial structure (as a continuation to ECE/TRANS/WP.29/GRBP/2021/9), the definition of snow tyres, the requirements for special use tyres of class C1, the addition of an optional prefix for extra load tyres, a clarification of the description of the load/speed test for run flat tyres and extended mobility tyres (EMT) and editorial corrections.

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 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 to amend the provisions for a pause function for reversing warning systems with the aim to comply with the national environmental (noise) restrictions.

Proposal for the Worn Tyres working group to complete the proposal for Supplement 1 to the 03 series of amendments to UN R117 (adopted by GRBP in September 2022 and submitted to the March 2023 WP.29 session) by adding a detailed reference (F3611-22) for the molded standard reference test tyre (SRTT16).

Proposal from the Worn Tyres working group to complete the proposal for the 04 series of amendments to UN R117 (adopted by GRBP in September 2022 and submitted to the March 2023 WP.29 session) by adding a detailed reference (F3611-22) for the molded standard reference test tyre (SRTT16).

Proposal to ensure that the test procedures for retreaded tyres are aligned with the text adopted by WP.29 per document WP.29/2021/8 for UN R117.

The existing transitional provisions do not address tyres produced in accordance with the applicable requirements and placed in distribution channels before 7 July 2026. Therefore, a new transitional provision is proposed based on the clause R.4 of part C – “Transitional provisions for replacement parts for vehicles in use” of the General Guidelines for United Nations Regulatory Procedures and Transitional Provisions in UN Regulations. It will clarify that new tyres manufactured before 7 July 2026 and approved according to the 02 or 03 series of amendment will be allowed to be sold and fitted on vehicles in use for additional period not exceeding 30 months from 7 July 2026.

Proposal to complete the additional sound emission provisions’ table of the communication form in the 05 series of amendments to UN R41 to avoid oversight in data collection and entries.

Proposal to explicitly allow other technical measurement solutions of the tyre overall width by removing the words “by calliper”, add the definition of “special tyre”, clarify the definition of “snow tyre”, to enable the case of a “special tyre” fulfilling the definition of a “snow” tyre, clarify application of the suffix “M/C”, and make editorial corrections and clarifications.

Proposal to delete obsolete footnotes concerning worn tyre wet grip and approvals under UN R117 coincident with approvals under UN R54. The 04 series of amendments to UN R117 introduces the requirements on adhesion of tyres in worn state on wet surfaces for tyres within the scope of UN R54.

Proposal to extend the scope of the speed category E to align with the technical evolution of agricultural and forestry vehicles.

The prescription given in paragraph 3.5.2., which will be implemented through document WP.29/2022/7/Rev.1 adopted by WP.29, contradicts the previously existing prescription in paragraph 3.2.9. This proposal aims to resolve the contradiction by amending paragraph 3.5.2. to introduce a reference to the prescriptions given in paragraph 3.2.9.

Proposal to address the following:

1. “Special use” tyres with nominal rim diameters larger than those listed in the present table (rim diameters up to 42, section widths up to 750 mm and overall diameters over 2 meters) and with speed symbols F and above have been announced in the European market as original equipment of N3G “special purpose vehicles” (i.e., special high speed self-propelled vehicles for agricultural and forestry use, like wood choppers).

2. Existing multi-purpose tyres (MPT) (classified as “special use tyres” as per paragraphs 2.5.3. and 3.1.13.), already type approved since years, have a tread pattern with lugs or cleats in addition to those with blocks, as evidenced by the attached slide showing some examples. It is proposed to amend paragraph 6.3.1. by clarifying that lugs and cleats are possible shapes of the mentioned blocks.

3. Testing tyres with very large overall diameters, sometimes over 2 m, on a test drum with a diameter of 1.70 m ± 1 % would be unpracticable. For practical reasons most of those
tyres are regularly tested on drums with a diameter of 3 m or even larger. The proposal carries equivalence provisions from UN R106 to justify the equivalence of the test method as required by Annex 7 in point 4 “Equivalent test methods" and clarifies based on UN R117 the formula already used indirectly.

4. Some commercial vehicles are often used in the market at a reduced speed of 70 km/h with a load-capacity of the tyres increased as per load/speed combination defined in the table of Annex 8. The proposal would allow use of the speed category symbol E (but restrict it to “additional service description”) to provide this information.

5. Considering that 32 km/h is already a floor value for the test-drum speed for diagonal tyres, ETRTO proposes not to apply to E speed category symbol tyres the linear decrease of
the test-drum speed in function of the decrease of the speed category symbol by keeping, for safety reasons, the same test-drum speed as for F speed category symbol tyres, i.e., 32 km/h).

6. In the case of additional service descriptions mentioned in paragraph 6.2.5.1., it is proposed not to perform the additional load/speed test because the load-capacity approximates with a negligeable difference the reduction or the increase in percentage of the nominal load/speed combination applicable to the nominal speed category symbol (see Annex 8).

7. Type approval applications for radial tyres with load capacity index greater or equal to 122 and without the additional marking “LT”, or “C” have been done in the past for the speed category symbol N for which the load/speed endurance test procedure is not described in Annex 7, Appendix 1. To type approve such tyres the test speed was separately defined by the different involved Type Approval Authorities. In order to harmonize the test procedure to be used for the type approval of such tyres, it is proposed to amend the Annex 7, Appendix 1 by introducing testing conditions in line with the rule applied for defining the test speed of radial tyres with load capacity index greater or equal to 122 (i.e. starting from 32 km/h set for F speed category symbol, the test speed is increased by 8 km/h respect to the one set for the previous speed category symbol).

8. The definition of “snow tyre” is amended to clarify that “snow tyres” are not only suitable for the use in snow conditions but also on mud and by replacing the term “maintain vehicle motion” (i.e. keeping the vehicle speed and direction of movement constant) by a more general concept of “controlling vehicle motion” (i.e. also being able to change the vehicle speed and direction of movement as intended).

9. It is proposed to explicitly allow other technical measurement solutions of the tyre overall width by removing the words “by caliper” which fix a technical limitation. The removal of this technical limitation would be advisable following the principle of not stopping the technical innovations.

10. Editorial corrections are introduced to ensure that the terms “load-capacity” and “speed category symbol” are used consistently throughout the text and to remove some typing mistakes present in the current text.

Proposal from the Informal Working Groups on Measurement Uncertainties (IWG MU) and Additional Sound Emission Provisions (ASEP) and from the International Organization for Standardization (ISO) for editorial corrections and clarifications based on the 03 series of amendments to UN R51 up to Supplement 7.