Continental Wintercontact Ts870P 255/40 R21

Continental Wintercontact Ts870P is a tyre made in total of 16 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 40mm wider than the narrowest dimension (215) and 30mm narrower than the widest one (285). 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.