285/40 R21 - Best tyres 2025 - market overview, tests, reviews

285/40 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 (285mm), which means the sidewall height has 114 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 235/55 R17(2168.64 mm), 235/65 R17(2316.3 mm), 155/70 R19(2197.86 mm), 245/35 R20(2134.71 mm), 165/60 R15(1818.98 mm), 245/45 R18(2129.06 mm), 170/80 R15(2051.46 mm).