Continental SportContact 6 is a summer tyre made in total of 187 sizes, ranging from R18 to R18 - this particular dimension is R21, which means it fits to a 21 inch/533.4mm diameter wheel. 325/30 R21 is 90mm wider than the narrowest dimension (235) and -30mm narrower than the widest one (295). This tyre profile of 30 means the sidewall height of the tyre is 30% of the tyre width (325mm), which results in 97.5mm sidewall height. In 325/30 R21, there is only one possible speed index for Continental SportContact 6 - "Y", which is good for speeds up to 300 km/h. In 325/30 R21, SportContact 6 usually competes against P ZERO, which is a tyre from Pirelli with a rating of 66%, compared to 90% of the Continental in question.