Division 2.2 Tyre selection requirements

Alignment tyre sets shall be selected for the laboratory alignment procedure in accordance with the following criteria. One alignment tyre set shall be selected for C1 tyres and C2 tyres together, and one set for C3 tyres:

1. (a)

   the alignment tyre set shall be selected so as to cover the range of different RRCs of C1 tyres and C2 tyres together, or of C3 tyres; in any event, the difference between the highest RRC_m of the alignment tyre set, and the lowest RRC_m of the alignment tyre set shall be, before and after alignment, at least equal to:

   1. (i)

      3 N/kN for C1 tyres and C2 tyres; and

   2. (ii)

      2 N/kN for C3 tyres;

2. (b)

   the RRC_m in the candidate or reference laboratories (RRC_m,c or RRC_m,l ) based on declared RRC values of each alignment tyre of the alignment tyre set shall be distributed evenly;

3. (c)

   load index values shall adequately cover the range of the tyres to be tested, ensuring that the rolling resistance values also cover the range of the tyres to be tested.

Each alignment tyre shall be checked prior to use and shall be replaced when:

1. (a)

   the alignment tyre shows a condition which makes it unusable for further tests; or

2. (b)

   there are deviations of RRC_m,c or RRC_m,l greater than 1,5 % relative to earlier measurements after correction for any machine drift.