Winter tyres tyre width 225 mm tyre cross section 50 rim diameter 17 inch load index 98 up to 750 kg speed rating v up to 149 mph installation all round tyre rolling resistance c wet grip b noise emission 72 db noise classification nc 2 runflat sipes directional tread symmetrical tread self sealing tyre runflat identification rft bridgestone run flat technology rft run flat tyres