Avon ZX7 255/55 R20

Avon ZX7 is a summer tyre made in total of 67 sizes, ranging from R13 to R13 - this particular dimension is R20, which means it fits to a 20 inch/508mm diameter wheel. 255/55 R20 is 40mm wider than the narrowest dimension (215) and 40mm narrower than the widest one (295). 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.