Nankang SP-9 Cross Sport is a tyre made in total of 27 sizes, ranging from R16 to R16 - this particular dimension is R20, which means it fits to a 20 inch/508mm diameter wheel. 245/50 R20 is 30mm wider than the narrowest dimension (215) and 70mm narrower than the widest one (315). This tyre profile of 50 means the sidewall height of the tyre is 50% of the tyre width (245mm), which results in 122.5mm sidewall height. In 245/50 R20, there is only one possible speed index for Nankang SP-9 Cross Sport - "", which is good for speeds up to km/h.