12. The expert from the Russian Federation introduced ECE/TRANS/WP.29/GRB/2011/11, aimed at improving the test provisions for measuring the rolling resistance of tyres. The proposal received several comments (GRB-54-02, GRB-54-08 and GRB-54-10 amongst others). The Chair of GRB introduced GRB-54-12-Rev.1 proposing to amend ECE/TRANS/WP.29/GRB/2011/11. He clarified that the proposal did not affect the existing methods but result in a further option to the deceleration method. GRB adopted ECE/TRANS/WP.29/GRB/2011/11 as reproduced by Annex III to this report. However, some GRB experts suggested further technical assessment of the proposed alternative method to the next GRB sessions. The secretariat was requested to submit the proposal to WP.29 and AC.1, for consideration at their March 2012 sessions, as draft Supplement 1 to the 02 series of amendments to Regulation No. 117.

13. GRB noted also the work progress of the Working Party on Brakes and Running Gear (GRRF) on matters of common interest with GRB (ECE/TRANS/WP.29/GRRF/2011/12, ECE/TRANS/WP.29/GRRF/2011/29, ECE/TRANS/WP.29/GRRF/2011/30, GRRF-69-23, GRRF-71-29 and GRRF-71-31). Particularly, GRB endorsed ECE/TRANS/WP.29/GRRF/2011/30, inserting a new definition of C3 class tyres adopted by GRRF at its September session.

15. Referring to the report of the September 2011 session of GRB (see ECE/TRANS/WP.29/GRB/52, para. 12), the Chair of GRB clarified that GRB-54-12-Rev.1 adopted at its September 2011 session, will not affect the existing test methods but will rather constitute an alternative to improve the accuracy of the deceleration method. The expert from ETRTO confirmed the clarification of the Chair. The expert from France supporting the adoption by WP.29 of GRB-54-12-Rev.1, expressed the need of detailed elaboration of the concept of tyre deceleration (dω/dt) in the test technology. The expert from the Russian Federation informed GRB about the initiative made by experts from his country to ETRTO to create a task force of industry experts on deceleration test; to further consider the test method development. The expert from the Russian Federation announced his intention to keep GRB informed about this initiative at its furture sessions.