Michelin Pilot Sport EV is a summer tyre made in total of 50 sizes, ranging from R19 to R19 - this particular dimension is R20, which means it fits to a 20 inch/508mm diameter wheel. 285/45 R20 is 50mm wider than the narrowest dimension (235) and -10mm narrower than the widest one (275). This tyre profile of 45 means the sidewall height of the tyre is 45% of the tyre width (285mm), which results in 128.25mm sidewall height. In 285/45 R20, there is only one possible speed index for Michelin Pilot Sport EV - "W", which is good for speeds up to 270 km/h.