Riken Ultra High Performance 255/45 R18

Riken Ultra High Performance is a tyre made in total of 55 sizes, ranging from R17 to R17 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 255/45 R18 is 50mm wider than the narrowest dimension (205) and -60mm narrower than the widest one (195). This tyre profile of 45 means the sidewall height of the tyre is 45% of the tyre width (255mm), which results in 114.75mm sidewall height.