Uniroyal MS plus 77 is a winter tyre made in total of 76 sizes, ranging from R13 to R13 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 235/40 R18 is 90mm wider than the narrowest dimension (145) and 20mm narrower than the widest one (255). This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (235mm), which results in 94mm sidewall height. In 235/40 R18, MS plus 77 usually competes against WR Snowproof, which is a tyre from Nokian with a rating of 55%, compared to 55% of the Uniroyal in question.