Continental UltraContact NXT is a summer tyre made in total of 22 sizes, ranging from R16 to R16 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 225/45 R18 is 20mm wider than the narrowest dimension (205) and 30mm narrower than the widest one (255). This tyre profile of 45 means the sidewall height of the tyre is 45% of the tyre width (225mm), which results in 101.25mm sidewall height. In 225/45 R18, there is only one possible speed index for Continental UltraContact NXT - "W", which is good for speeds up to 270 km/h. In 225/45 R18, UltraContact NXT usually competes against Eagle F1 Asymmetric 6, which is a tyre from Goodyear with a rating of 93%, compared to 95% of the Continental in question.