Nexen N fera Sport is a summer tyre made in total of 94 sizes, ranging from R16 to R16 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 235/40 R18 is 30mm wider than the narrowest dimension (205) and 50mm narrower than the widest one (285). This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (235mm), which results in 94mm sidewall height. In 235/40 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 235/40 R18, N fera Sport usually competes against Quatrac Pro+, which is a tyre from Vredestein with a rating of 58%, compared to 67% of the Nexen in question.