Royal Black Royal Performance 255/40 R18

Royal Black Royal Performance is a tyre made in total of 68 sizes, ranging from R15 to R15 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 255/40 R18 is 60mm wider than the narrowest dimension (195) and 30mm narrower than the widest one (285). 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.