Nokian WR A4 is a winter tyre made in total of 59 sizes, ranging from R16 to R16 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 235/45 R18 is 30mm wider than the narrowest dimension (205) and 10mm narrower than the widest one (245). This tyre profile of 45 means the sidewall height of the tyre is 45% of the tyre width (235mm), which results in 105.75mm sidewall height. In
235/45 R18, WR A4 usually competes against
ContiWinterContact TS 850P, which is a tyre from
Continental with a rating of 0%, compared to 0% of the
Nokian in question.