Consolidated version integrating GRBP/2022/13, GRBP/2022/16 and GRBP-76-09 as adopted during the 76th GRBP session and including corrections and clarifications per GRBP/2023/12.

Proposal from the Informal Working Group on Measurement Uncertainties (IWG MU) to amend UN R51 with tables showing the measurement uncertainties when performing type-approval, COP, or field testing (e.g. market surveillance).

The measurement uncertainties developed in this Appendix are based the IWG MU work and its Document for Reference which describes a general approach to estimate measurement uncertainties (GRBP/2022/9/Rev.2). The impact of the quantities on the expanded uncertainty has been evaluated separately for run-to-run, day-to-day, vehicle-to-vehicle and site-to-site variations. Some of the different impacts are based on calculations from tolerances in Annex 3, while others are based on experiences.

Report on discussions concerning the feasibility of a new UN Regulation on uniform provisions for the approval of pre-cured tread materials used for producing retreaded tyres or the approval of retreaded tyres produced by using mould cure process with regard to their snow performance.

Outcomes from discussions in the GRBP Special Interest Group on AV Regulatory Screening.

Proposal from the Noise Measurement Uncertainties informal group for amendments to Annex 3.

Proposal to replace GRBP/2023/11 with a revised 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). An example of the actual differences (in percentage and in absolute value) is provided.

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.

Request to allocate time on the agenda of the 78th session for consideration of performance requirements for tyres used on heavy-duty pickup trucks designed for professional tasks on rough terrains.

Proposal to supersede GRBP/2023/10 with a more flexible approach appropriate for covering the operations of small retreaders.

Editorial amendment to align the definition of “special tyre” with the proposal for the snow tyre definition in paragraph 2.33.

Proposal to clarify the details of the data-handling during the monitoring phase required in paragraph 5.1.1.