Goodyear Efficientgrip is a summer tyre made in total of 86 sizes, ranging from R14 to R14 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 255/40 R18 is 70mm wider than the narrowest dimension (185) and 30mm narrower than the widest one (285). This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (255mm), which results in 102mm sidewall height. In 255/40 R18, there are 3 possible speed indexes for Goodyear Efficientgrip - "V","W","Y", which are good for speeds up to 240, 270, 300 km/h.
