245/40 R21 - Best tyres 2026 - 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 225/55 R16(2054.29 mm), 295/35 R21(2324.46 mm), 225/65 R16(2195.66 mm), 315/35 R20(2288.65 mm), 235/40 R17(1947.16 mm), 235/50 R18(2174.61 mm), 235/60 R18(2322.27 mm).