275/45 R21 - Best tyres 2025 - market overview, tests, reviews

275/45 R21 doesn't belong to the most popular dimensions for tyres - there are tyre models available, which can be compared to 325/30 R21, 155/60 R15, 155/65 R13. Let's break down the sizing - 45 is height of the tyre, which is calculated as 45% of the tyre width (275mm), which means the sidewall height has 123.75 mm. The wheel diameter is R21, which means it fits to a 21 inch/533.4mm diameter wheel. The total circumference of the tyre is mm, which is very similar to 225/60 R17(2204.77 mm), 305/30 R20(2170.84 mm), 235/35 R19(2032.92 mm), 235/45 R20(2260.38 mm), 235/60 R16(2162.67 mm), 155/60 R15(1781.28 mm), 235/85 R16(2531.81 mm).