UN R117 — Supplement 13 to the 02 series of amendments

Paragraph 2.18. now refers to the standards of ASTM International, and item (e) now refers to F2493 – 19 for SRTT16. Before, item (e) referred to F2493 – 18. The wet grip index (G) now means the wet grip performance of a candidate tyre relative to that of the applicable standard reference test tyre. The snow grip index (SG) now means the snow grip performance of a candidate tyre relative to the performance of the applicable SRTT. Before, both indices were defined as the ratio between the performance of the candidate tyre and the performance of the standard reference test tyre. The control tyre definition now refers to paragraph 2.2.2.8. of Annex 5, part (B), instead of paragraph 4.1.7. of Annex 5.

Paragraph 4.4. now covers the markings referred to in paragraph 4.2. and the approval mark prescribed in paragraph 5.4. They must be clearly legible, indelible and raised above or sunk below the tyre surface. Before, the approval mark had to be moulded into or onto the sidewall of the tyre. Paragraph 4.4.1. now says that the approval mark must be situated in the lower area of the tyre on at least one of its sidewalls. For tyres with the “tyre to rim fitment configuration” symbol “A” or the new “U”, the markings may be located anywhere on the outside sidewall. Paragraph 5.4.4. now refers to paragraph 5.2.2. instead of 5.3.2., and paragraphs 7.1.3. and 7.1.4. are renumbered as 7.2. and 7.3.

New paragraph 4.3.1. applies when the same Type Approval Authority grants the approval under this Regulation and under UN Regulation No. 30 or No. 54. Then the approval mark under UN Regulation No. 30 or No. 54 can be combined with the paragraph 5.2.2. suffixes, with the addition sign “+”. The combination also shows the UN Regulation No. 117 series of amendments in 2 digits, for example “0236378 + 02S1WR2”. The title of Annex 2, Appendix 3 is now “Combinations of markings of approvals issued in accordance with UN Regulations Nos. 117, 30 or 54”. In both examples, the “+ 02S1” and “+ 02S1WR2” markings now indicate that the tyre was also approved pursuant to Regulation No. 117 (02 series of amendments). A footnote that said “Approvals in accordance with Regulation No. 117 for tyres within the scope of Regulation No. 54 currently do not include wet adhesion requirements” is deleted.

In the table of paragraph 6.4.1.1., two reference tyre entries now read “Ref.s = SRTT14, SRTT16” instead of “Ref. = SRTT14”. In Annex 7, the traction test now uses ASTM F1805-06 when SRTT14 is the reference tyre, or ASTM F1805-20 when SRTT16 is the reference tyre. When SRTT16 is the reference tyre, it must be tested with a load of 531 kg at an inflation pressure of 240 kPa (cold). New paragraph 2.3. computes the snow grip index (SG) from the traction performance index (TPI), with a factor f that depends on the reference tyre. New paragraph 3.1.6. requires the SRTT shown in a table: SRTT14 or SRTT16 for Class C1 tyres, and SRTT16C for Class C2 tyres. Paragraph 3.4.1.3. now takes a factor f from a table of tyre class and reference tyre.

Annex 5 now has the title “Test procedures for measuring the wet grip index of new tyres”. Under paragraph 3.1.5., SRTT16 now measures the wetted frictional properties of the surface, for the vehicle and the trailer (or tyre test vehicle) method. Before, the methods in paragraph 3.2. were the British Pendulum Number (BPN) method and the Standard Reference Test Tyre method. The wet grip index G(Tn) now uses new formulas with the factors Kvehicle = 1.87 and Ktrailer = 1.50. If a candidate tyre and reference tyre cannot be compared directly on the same vehicle, the trailer or tyre test vehicle method must be used. Before, paragraph 4.1.7. covered a wet grip comparison between a candidate tyre and a reference tyre using a control tyre.

In Annex 5, Part (B), the Standard Reference Test Tyre (SRTT) method now uses SRTT16 instead of SRTT14. The braking test of the reference tyre is done in the same area where the average macro texture depth was measured. It has at least six (6) valid test runs in the same direction. If the coefficient of variation CVµ exceeds 4 per cent, the results are dismissed and the braking test is repeated. The temperature corrected µpeak,corr must now be not less than 0.65 and not greater than 0.90, instead of 0.7 ± 0.1. Paragraph 1.1.2., the British Pendulum Number (BPN) method, is deleted, and paragraph 1.1.3. is renumbered as 1.1.2.

Until 3 months after Supplement 13 enters into force, Contracting Parties applying this Regulation can continue to grant 02 series approvals without it (paragraph 12.10.). Until 1 September 2024, Contracting Parties may continue to grant 02 series approvals based on the Annex 7 snow test with SRTT14 as reference tyre. Until 1 September 2024, Contracting Parties may continue to grant 02 series approvals based on the Annex 5 wet grip test procedures without Supplement 13. A new footnote says that SRTT14 will be available from the supplier until end of October 2021.