Dunlop SPORTSMART TT is a winter tyre made in total of 13 sizes, ranging from R17 to R17 - this particular dimension is R17, which means it fits to a 17 inch/431.8mm diameter wheel. 200/55 R17 is 90mm wider than the narrowest dimension (110) and -80mm narrower than the widest one (120). This tyre profile of 55 means the sidewall height of the tyre is 55% of the tyre width (200mm), which results in 110mm sidewall height. In 200/55 R17, there is only one possible speed index for Dunlop SPORTSMART TT - "W", which is good for speeds up to 270 km/h.