Michelin Pilot Sport 4 S 275/25 R21

Michelin Pilot Sport 4 S is a summer tyre made in total of 195 sizes, ranging from R18 to R18 - this particular dimension is R21, which means it fits to a 21 inch/533.4mm diameter wheel. 275/25 R21 is 70mm wider than the narrowest dimension (205) and 40mm narrower than the widest one (315). This tyre profile of 25 means the sidewall height of the tyre is 25% of the tyre width (275mm), which results in 68.75mm sidewall height.