Michelin Pilot Sport 4S is a summer tyre made in total of 34 sizes, ranging from R18 to R18 - this particular dimension is R20, which means it fits to a 20 inch/508mm diameter wheel. 275/30 R20 is 20mm wider than the narrowest dimension (255) and 50mm narrower than the widest one (325). This tyre profile of 30 means the sidewall height of the tyre is 30% of the tyre width (275mm), which results in 82.5mm sidewall height. In 275/30 R20, there is only one possible speed index for Michelin Pilot Sport 4S - "Y", which is good for speeds up to 300 km/h. In 275/30 R20, Pilot Sport 4S usually competes against Ventus S1 evo3 K127, which is a tyre from Hankook with a rating of 82%, compared to 0% of the Michelin in question.