Proposal to maintain a wet grip index of 0.65 for class C3 normal tires and regular snow tires under the discussions to establish wet grip provisions and testing procedures for category C2 and C3 tires.
24. Recalling the purpose of ECE/TRANS/WP.29/2013/66, the Chair of GRRF stressed that WP.29 was expecting GRRF to conclude its deliberation about the wet grip limit values. The GRRF experts introduced their positions (GRRF-76-05, GRRF-76-07, GRRF-76-08, GRRF-76-11, GRRF-76-12, GRRF-76-26, GRRF-76-27, GRRF-76-28). The expert from the EC reported on the concerns expressed by the Directorate-General for Mobility and Transport of the European Commission (DG Move). GRRF confirmed the limit values proposed in para. 6.2.2. for Tyres of C2 category and agreed to amend the proposed limit values in para. 6.2.3. for Tyres of C3 category in ECE/TRANS/WP.29/2013/66. GRRF requested the secretariat to submit this amendment as reproduced in WP.29-162-05 to WP.29 and AC.1 for consideration at their March 2014 session.
24bis. The expert from the Russian Federation presented GRB-59-02 proposing a tyre rolling resistance test results evaluation using a mathematical algorithm, to be added as an alternative to the existing one in the text of the Regulation. He also presented the results of a validation study of the proposed algorithm for tyres of the C1 category performed in France, in cooperation with the Russian Federation (GRB-59-07 and GRB-59-08). GRRF noted that this proposal may be submitted by GRB to WP.29 as a supplement to UN Regulation No. 117. GRRF recommended further steps for a better understanding of the proposed method’s sensitivity, suggesting: (i) extending the validation study for tyres of categories C2 and C3 and (ii) verifying the application of the proposed alternative in the conditions of the conformity of production. The GRRF Chair invited the experts to provide their comments on the proposal to the GRB secretariat with a copy to the expert from the Russian Federation.