Dunlop SP Sport MAXX GT is a summer tyre made in total of 118 sizes, ranging from R17 to R17 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 245/50 R18 is 10mm wider than the narrowest dimension (235) and 70mm narrower than the widest one (315). This tyre profile of 50 means the sidewall height of the tyre is 50% of the tyre width (245mm), which results in 122.5mm sidewall height. In 245/50 R18, there are 2 possible speed indexes for Dunlop SP Sport MAXX GT - "W","Y", which are good for speeds up to 270, 300 km/h. In 245/50 R18, SP Sport MAXX GT usually competes against Ultrac Vorti, which is a tyre from Vredestein with a rating of 55%, compared to 0% of the Dunlop in question.