Bridgestone Potenza Sport is a summer tyre made in total of 132 sizes, ranging from R17 to R17 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (205mm), which results in 82mm sidewall height. In 205/40 R18, there is only one possible speed index for Bridgestone Potenza Sport - "H", which is good for speeds up to 210 km/h. In 205/40 R18, Potenza Sport usually competes against Pilot Sport 4, which is a tyre from Michelin with a rating of 88%, compared to 92% of the Bridgestone in question.