Yokohama BLUEARTH-GT AE51 is a summer tyre made in total of 59 sizes, ranging from R14 to R14 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 225/40 R18 is 70mm wider than the narrowest dimension (155) and 20mm narrower than the widest one (245). This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (225mm), which results in 90mm sidewall height. In 225/40 R18, there is only one possible speed index for Yokohama BLUEARTH-GT AE51 - "W", which is good for speeds up to 270 km/h. In 225/40 R18, BLUEARTH-GT AE51 usually competes against ZEON CS8, which is a tyre from Cooper with a rating of 42%, compared to 0% of the Yokohama in question.