14. GRB considered ECE/TRANS/WP.29/GRRF/2013/9 for the next session of the Working Party on Brakes and Running Gear (GRRF). The document proposes wet grip provisions and testing procedures for tyres of categories C2 and C3. GRB endorsed ECE/TRANS/WP.29/GRRF/2013/9 without amendments.

15. GRB resumed discussion on ECE/TRANS/WP.29/GRB/2012/11, amended by GRB-57-03. The expert from EC expressed reservation on the term of differential lock that could lead to misconception. GRB endorsed the reservation of the expert from EC and agreed to inform GRRF.

16. The expert from ETRTO introduced ECE/TRANS/WP.29/GRB/2013/5, drafted in cooperation with the experts from Poland and the United Kingdom, proposing to update the test track requirements to ISO 10844:2011 as a supplement to the UN Regulation rather than a new series of amendments. He stated that the new test track with tighter tolerances would maintain the same nominal noise behaviour and that its introduction as a new series of amendments was not justified (GRB-57-02). The experts from France endorsed the proposal and stated that technical variations introduced by the new track would not justify a new series of amendments. The experts from Italy and Japan also endorsed ECE/TRANS/WP.29/GRB/2013/5.

17. GRB finally adopted ECE/TRANS/WP.29/GRB/2013/5 (superseding ECE/TRANS/WP.29/GRB/2013/2, ECE/TRANS/WP.29/GRB/2012/15 and ECE/TRANS/WP.29/GRB/2012/18) as reproduced in Annex II to this report. The secretariat was requested to submit the proposal to WP.29 and AC.1 for consideration and vote at their June 2013 sessions as draft Supplement 4 to the 07 series of amendments to UN Regulation No. 117. Moreover, GRB agreed that extensions of type approvals, granted by using the test track in accordance to ISO 10844:1994, may be carried out with the test track built in accordance with ISO 10844:2011, taking into account that this last would not negatively affect type approval noise test results.

18. The expert from the Russian Federation introduced ECE/TRANS/WP.29/GRB/2013/3, amended by GRB-57-01, proposing the use of a “Deceleration Calculator” software for the deceleration test method in the test procedure for measuring rolling resistance. He informed GRB about the variant of data processing in the rolling resistance deceleration test method basing on the dω/dt formula. He underlined that this variant was used as an alternative to the existing data processing stipulated in UN Regulation No. 117, not affecting the existing test methods, and that it fully matches ISO 28580 and the procedures of Annex 6 of UN Regulation No. 117. The “Deceleration calculator” is a mathematical tool providing high accuracy [σ < 0.001%; R2 > 0.999] of development in the experimental data. The concept dω/dt was incorporated into standard GOST R 52102.1 He also introduced GRB-57-25 to provide a background history on the development of legislation on rolling resistance and made a practical demonstration of the proposed “Calculator”.

19. GRB recommended that experts start using the proposed calculator and to provide comments at its September 2013 session. The expert from the Russian Federation was recommended to provide, in the meantime, further background information on the algorithms of the calculator and on both proposals (ECE/TRANS/WP.29/GRB/2013/3 and GRB-57-01), as well as demonstration at the next session of GRRF for an exchange of views.

20. Concerning the concept of a new tyre contained in the scope of the UN Regulation, the expert from ETRTO stated that “a new tyre means a tyre which has been never used nor subjected to retreading operation and arriving directly from the production process”. GRB endorsed this concept.