Radar Dimax Alpine is a winter tyre made in total of 21 sizes, ranging from R15 to R15 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 225/40 R18 is 30mm wider than the narrowest dimension (195) and 10mm narrower than the widest one (235). 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 Radar Dimax Alpine - "V", which is good for speeds up to 240 km/h. In 225/40 R18, Dimax Alpine usually competes against winter W2, which is a tyre from Giti with a rating of 55%, compared to 51% of the Radar in question.