Kumho Ecsta PS91 is a summer tyre made in total of 48 sizes, ranging from R18 to R18 - this particular dimension is R20, which means it fits to a 20 inch/508mm diameter wheel. 275/40 R20 is 50mm wider than the narrowest dimension (225) and 0mm narrower than the widest one (275). 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 Kumho Ecsta PS91 - "Y", which is good for speeds up to 300 km/h. In 275/40 R20, Ecsta PS91 usually competes against Advan Sport V105, which is a tyre from Yokohama with a rating of 0%, compared to 21% of the Kumho in question.