Michelin Pilot Sport 5 Energy 255/40 R21

Michelin Pilot Sport 5 Energy is a summer tyre made in total of 40 sizes, ranging from R18 to R18 - this particular dimension is R21, which means it fits to a 21 inch/533.4mm diameter wheel. 255/40 R21 is 20mm wider than the narrowest dimension (235) and 60mm narrower than the widest one (315). 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.