Yokohama BluEarth winter V905 315/40 R21

Yokohama BluEarth winter V905 is a winter tyre made in total of 502 sizes, ranging from R13 to R13 - this particular dimension is R21, which means it fits to a 21 inch/533.4mm diameter wheel. 315/40 R21 is 170mm wider than the narrowest dimension (145) and 0mm narrower than the widest one (315). This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (315mm), which results in 126mm sidewall height.