Goodyear Eagle F1 Supersport 305/30 R21

Goodyear Eagle F1 Supersport is a summer tyre made in total of 143 sizes, ranging from R18 to R18 - this particular dimension is R21, which means it fits to a 21 inch/533.4mm diameter wheel. 305/30 R21 is 100mm wider than the narrowest dimension (205) and -30mm narrower than the widest one (275). This tyre profile of 30 means the sidewall height of the tyre is 30% of the tyre width (305mm), which results in 91.5mm sidewall height.