Metzeler ME 888 Marathon Ultra 180/50 R21

Metzeler ME 888 Marathon Ultra is a summer tyre made in total of 127 sizes, ranging from R13 to R13 - this particular dimension is R21, which means it fits to a 21 inch/533.4mm diameter wheel. 180/50 R21 is 40mm wider than the narrowest dimension (140) and 0mm narrower than the widest one (180). This tyre profile of 50 means the sidewall height of the tyre is 50% of the tyre width (180mm), which results in 90mm sidewall height.