Pirelli P Zero Trofeo R is a summer tyre made in total of 4 sizes, ranging from R18 to R18 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 295/30 R18 is 60mm wider than the narrowest dimension (235) and -50mm narrower than the widest one (245). This tyre profile of 30 means the sidewall height of the tyre is 30% of the tyre width (295mm), which results in 88.5mm sidewall height. In 295/30 R18, there is only one possible speed index for Pirelli P Zero Trofeo R - "Y", which is good for speeds up to 300 km/h.