2.25.3.4. On radial ply tyres suitable for speeds in excess of 240 km/h but not exceeding 300 km/h (tyres marked with the speed symbol "W" or "Y" as part of the service description), the letter "R", placed before the rim diameter marking, may be replaced with the inscription "ZR"; on tyres suitable for speeds in excess of 300 km/h, the letter "R" placed in front of the rim diameter marking shall be replaced by the inscription "ZR"; a7c0