Michelin Pilot Sport 5 is a summer tyre made in total of 53 sizes, ranging from R17 to R17 - this particular dimension is R20, which means it fits to a 20 inch/508mm diameter wheel. 255/40 R20 is 50mm wider than the narrowest dimension (205) and 0mm narrower than the widest one (255). This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (255mm), which results in 102mm sidewall height. In 255/40 R20, there is only one possible speed index for Michelin Pilot Sport 5 - "Y", which is good for speeds up to 300 km/h. In 255/40 R20, Pilot Sport 5 usually competes against Eagle F1 Asymmetric 6, which is a tyre from Goodyear with a rating of 100%, compared to 97% of the Michelin in question.