245/40 R21 - Best tyres 2025 - market overview, tests, reviews

245/40 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 (245mm), which means the sidewall height has 98 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 185/70 R14(1930.82 mm), 255/60 R18(2397.66 mm), 195/45 R16(1828.09 mm), 265/30 R21(2175.24 mm), 195/60 R16(2011.88 mm), 265/40 R19(2182.15 mm), 195/80 R15(2177.12 mm).