275/40 R21 - Best tyres 2025 - market overview, tests, reviews

275/40 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 - 40 is height of the tyre, which is calculated as 40% of the tyre width (275mm), which means the sidewall height has 110 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 195/55 R15(1870.82 mm), 265/35 R18(2019.1 mm), 195/65 R16(2073.14 mm), 265/40 R21(2341.74 mm), 205/40 R17(1871.76 mm), 265/65 R17(2438.82 mm), 205/55 R16(1985.17 mm).