Nexen N FERA SPORT SUV is a summer tyre made in total of 23 sizes, ranging from R16 to R16 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 235/45 R18 is 20mm wider than the narrowest dimension (215) and 0mm narrower than the widest one (235). This tyre profile of 45 means the sidewall height of the tyre is 45% of the tyre width (235mm), which results in 105.75mm sidewall height. In 235/45 R18, there is only one possible speed index for Nexen N FERA SPORT SUV - "W", which is good for speeds up to 270 km/h.