Winter tyres tyre width 255 mm tyre cross section 55 rim diameter 18 inch load index 109 up to 1030 kg speed rating h up to 130 mph rolling resistance f wet grip e noise emission 73 db noise classification nc 2 runflat rim protector runflat identification ssr csr sst continental run flat technology ssr self supporting runflat tyre rim protection marking fp mfs fr fl fsl ml rpb