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. 255/45 R18 is 100mm wider than the narrowest dimension (155) and -10mm narrower than the widest one (245). This tyre profile of 45 means the sidewall height of the tyre is 45% of the tyre width (255mm), which results in 114.75mm sidewall height. In 255/45 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 255/45 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.