GT radial Sport Active 255/55 R18

GT radial Sport Active is a summer tyre made in total of 18 sizes, ranging from R17 to R17 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 255/55 R18 is 50mm wider than the narrowest dimension (205) and 0mm narrower than the widest one (255). This tyre profile of 55 means the sidewall height of the tyre is 55% of the tyre width (255mm), which results in 140.25mm sidewall height.