Pirelli WINTER SOTTOZERO Serie III is a winter tyre made in total of 228 sizes, ranging from R16 to R16 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 225/55 R18 is 20mm wider than the narrowest dimension (205) and 130mm narrower than the widest one (355). This tyre profile of 55 means the sidewall height of the tyre is 55% of the tyre width (225mm), which results in 123.75mm sidewall height. In 225/55 R18, there are 2 possible speed indexes for Pirelli WINTER SOTTOZERO Serie III - "H","V", which are good for speeds up to 210, 240 km/h. In 225/55 R18, WINTER SOTTOZERO Serie III usually competes against SP Sport MAXX RT2, which is a tyre from Dunlop with a rating of 72%, compared to 0% of the Pirelli in question.