Continental EcoContact 6 is a summer tyre made in total of 307 sizes, ranging from R13 to R13 - this particular dimension is R21, which means it fits to a 21 inch/533.4mm diameter wheel. 255/40 R21 is 100mm wider than the narrowest dimension (155) and 60mm narrower than the widest one (315). This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (255mm), which results in 102mm sidewall height. In 255/40 R21, there is only one possible speed index for Continental EcoContact 6 - "V", which is good for speeds up to 240 km/h. In 255/40 R21, EcoContact 6 usually competes against Turanza T005, which is a tyre from Bridgestone with a rating of 89%, compared to 63% of the Continental in question.