Proposal to standardize provisions for the water depth measurement, reduce the track friction range requirements under the test procedures, clarfy that adhesion performance on wet surfaces (wet adhesion) is required not only for C1 tyres, but also C2 and C3 tyres, update the standards references to ASTM F2493-244, F3611-24, F3676-24, F3675-24 and ISO 4000-1:2024, align the definitions of tread groove and principal grooves with proposals for UN R30 and R54, simplify the wording of the requirements for professional off-road tyres, and correct the transitional provision in paragraph 12.23. to specify approvals “first issued after 31 August 2028”.

Proposal to

1. Update standard reference to ASTM F2493-24 and ISO 4000-1:2024
2. Align the definitions of tread groove and principal grooves with proposals for UN R30 and R54
3. Simplify the wording of the requirements for professional off-road tyres
4. Correct the transitional provision in paragraph 12.23. to specify approvals “first issued after 31 August 2028”.

Proposal to introduce measures to reduce variability in noise measurements and new test methods to measure tyre abrasion.

Proposal to revise the limits for rolling resistance and wet grip, to address tyres for vintage vehicles, to revise the definition for special-use C1 tyres, and to set the wet grip index threshold at 0.80 for class C1 tyres with a nominal aspect ratio equal to or less than 40, a section width equal to or higher than 235 mm and suitable for speeds equal to or greater than 300 km/h and for class C1 all terrain and special use tyres. The proposal also introduces the k_worn factor in a new para. 3 in Annex 9 to address wet grip of C2 and C3 tyres in a worn state (see GRBP-75-26-Rev.1 for concept), provisions to allow the type approval of special use tyres that fulfil the requirements for snow performance as laid out in Annex 7, and a new definition of traction elements to characterize traction tyres.