Nokian WR Snowproof P is a winter tyre made in total of 55 sizes, ranging from R17 to R17 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 235/45 R18 is 30mm wider than the narrowest dimension (205) and 10mm narrower than the widest one (245). This tyre profile of 45 means the sidewall height of the tyre is 45% of the tyre width (235mm), which results in 105.75mm sidewall height. In 235/45 R18, there is only one possible speed index for Nokian WR Snowproof P - "V", which is good for speeds up to 240 km/h. In 235/45 R18, WR Snowproof P usually competes against Snowprox S954, which is a tyre from Toyo with a rating of 43%, compared to 44% of the Nokian in question.