Nokian Powerproof 2 255/40 R21

Nokian Powerproof 2 is a summer tyre made in total of 91 sizes, ranging from R16 to R16 - this particular dimension is R21, which means it fits to a 21 inch/533.4mm diameter wheel. 255/40 R21 is 50mm wider than the narrowest dimension (205) 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.