Nokian Rotiiva AT 255/70 R18

Nokian Rotiiva AT is a winter tyre made in total of 33 sizes, ranging from R13 to R13 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 255/70 R18 is 20mm wider than the narrowest dimension (235) and 30mm narrower than the widest one (285). This tyre profile of 70 means the sidewall height of the tyre is 70% of the tyre width (255mm), which results in 178.5mm sidewall height.