Pirelli P ZERO PZ4 is a summer tyre made in total of 338 sizes, ranging from R17 to R17 - this particular dimension is R21, which means it fits to a 21 inch/533.4mm diameter wheel. 275/45 R21 is 50mm wider than the narrowest dimension (225) and 60mm narrower than the widest one (335). This tyre profile of 45 means the sidewall height of the tyre is 45% of the tyre width (275mm), which results in 123.75mm sidewall height. In 275/45 R21, there are 2 possible speed indexes for Pirelli P ZERO PZ4 - "Y","H", which are good for speeds up to 300, 210 km/h. In 275/45 R21, P ZERO PZ4 usually competes against P ZERO, which is a tyre from Pirelli with a rating of 61%, compared to 93% of the Pirelli in question.