Nexen N fera Sport is a summer tyre made in total of 20 sizes, ranging from R17 to R17 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 235/45 R18 is 10mm wider than the narrowest dimension (225) 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 (235mm), which results in 105.75mm sidewall height. In 235/45 R18, there is only one possible speed index for Nexen N fera Sport - "Y", which is good for speeds up to 300 km/h. In 235/45 R18, N fera Sport usually competes against Aspire XP, which is a tyre from Apollo with a rating of 53%, compared to 76% of the Nexen in question.