Barum Polaris 3 is a winter tyre made in total of 65 sizes, ranging from R13 to R13 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 255/40 R18 is 120mm wider than the narrowest dimension (135) and -10mm narrower than the widest one (245). This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (255mm), which results in 102mm sidewall height. In 255/40 R18, Polaris 3 usually competes against Radial Champiro WinterPro 2, which is a tyre from GT with a rating of 60%, compared to 0% of the Barum in question.