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 205/80 R16(2307.19 mm), 275/45 R18(2213.88 mm), 215/50 R17(2031.98 mm), 275/65 R18(2559.46 mm), 215/65 R16(2154.82 mm), 285/35 R20(2222.68 mm), 225/35 R18(1931.14 mm).