Pirelli Cinturato P7 is a summer tyre made in total of 205 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 40mm wider than the narrowest dimension (195) and -40mm narrower than the widest one (195). 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 Pirelli Cinturato P7 - "W", which is good for speeds up to 270 km/h. In 235/40 R18, Cinturato P7 usually competes against Ventus Prime3 K125, which is a tyre from Hankook with a rating of 75%, compared to 75% of the Pirelli in question.