285/40 R21 - Best tyres 2026 - 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 285/35 R19(2142.88 mm), 225/35 R18(1931.14 mm), 285/45 R20(2401.75 mm), 225/50 R16(1983.6 mm), 295/30 R20(2151.99 mm), 225/60 R16(2124.97 mm), 305/25 R20(2075.02 mm).