Michelin Primacy 4 255/45 R21

Michelin Primacy 4 is a summer tyre made in total of 367 sizes, ranging from R14 to R14 - this particular dimension is R21, which means it fits to a 21 inch/533.4mm diameter wheel. 255/45 R21 is 100mm wider than the narrowest dimension (155) and 50mm narrower than the widest one (305). This tyre profile of 45 means the sidewall height of the tyre is 45% of the tyre width (255mm), which results in 114.75mm sidewall height.