Yokohama BluEarth-4S AW21 is a allround tyre made in total of 66 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 50mm wider than the narrowest dimension (175) and 40mm narrower than the widest one (265). 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-4S AW21 - "W", which is good for speeds up to 270 km/h. In 225/40 R18, BluEarth-4S AW21 usually competes against Weather Control A005 EVO, which is a tyre from Bridgestone with a rating of 62%, compared to 31% of the Yokohama in question.