Vredestein Ultrac Pro is a summer tyre made in total of 40 sizes, ranging from R18 to R18 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 245/45 R18 is 20mm wider than the narrowest dimension (225) and 110mm narrower than the widest one (355). This tyre profile of 45 means the sidewall height of the tyre is 45% of the tyre width (245mm), which results in 110.25mm sidewall height. In 245/45 R18, there is only one possible speed index for Vredestein Ultrac Pro - "Y", which is good for speeds up to 300 km/h. In 245/45 R18, Ultrac Pro usually competes against Pilot Sport 5, which is a tyre from Michelin with a rating of 97%, compared to 87% of the Vredestein in question.