Kumho Ecsta PS71 is a summer tyre made in total of 135 sizes, ranging from R16 to R16 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 245/40 R18 is 50mm wider than the narrowest dimension (195) and 40mm narrower than the widest one (285). This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (245mm), which results in 98mm sidewall height. In 245/40 R18, there is only one possible speed index for Kumho Ecsta PS71 - "Y", which is good for speeds up to 300 km/h. In 245/40 R18, Ecsta PS71 usually competes against RainSport 3, which is a tyre from Uniroyal with a rating of 56%, compared to 77% of the Kumho in question.