Pirelli P ZERO Rosso is a summer tyre made in total of 45 sizes, ranging from R16 to R16 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 225/40 R18 is 20mm wider than the narrowest dimension (205) and 70mm narrower than the widest one (295). This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (225mm), which results in 90mm sidewall height. In 225/40 R18, there is only one possible speed index for Pirelli P ZERO Rosso - "Y", which is good for speeds up to 300 km/h. In 225/40 R18, P ZERO Rosso usually competes against Ventus Prime3 K125, which is a tyre from Hankook with a rating of 75%, compared to 0% of the Pirelli in question.