Dunlop SP Sport MAXX RT2 is a summer tyre made in total of 101 sizes, ranging from R17 to R17 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. This tyre profile of 45 means the sidewall height of the tyre is 45% of the tyre width (205mm), which results in 92.25mm sidewall height. In 205/45 R18, there is only one possible speed index for Dunlop SP Sport MAXX RT2 - "Y", which is good for speeds up to 300 km/h.