Bridgestone Turanza ER300 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. 275/40 R18 is 90mm wider than the narrowest dimension (185) 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 R18, there is only one possible speed index for Bridgestone Turanza ER300 - "Y", which is good for speeds up to 300 km/h. In 275/40 R18, Turanza ER300 usually competes against POTENZA SPORT EVO, which is a tyre from Bridgestone with a rating of 87%, compared to 0% of the Bridgestone in question.