Nokian Powerproof SUV is a summer tyre made in total of 29 sizes, ranging from R17 to R17 - this particular dimension is R20, which means it fits to a 20 inch/508mm diameter wheel. 275/40 R20 is 40mm wider than the narrowest dimension (235) and 20mm narrower than the widest one (295). This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (275mm), which results in 110mm sidewall height. In 275/40 R20, there is only one possible speed index for Nokian Powerproof SUV - "Y", which is good for speeds up to 300 km/h. In 275/40 R20, Powerproof SUV usually competes against RainSport 5, which is a tyre from Uniroyal with a rating of 62%, compared to 0% of the Nokian in question.