Dunlop SP Winter Sport 4D is a winter tyre made in total of 43 sizes, ranging from R15 to R15 - this particular dimension is R20, which means it fits to a 20 inch/508mm diameter wheel. 295/40 R20 is 100mm wider than the narrowest dimension (195) and -10mm narrower than the widest one (285). This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (295mm), which results in 118mm sidewall height. In 295/40 R20, there is only one possible speed index for Dunlop SP Winter Sport 4D - "V", which is good for speeds up to 240 km/h.