285/35 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 - 35 is height of the tyre, which is calculated as 35% of the tyre width (285mm), which means the sidewall height has 99.75 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 285/65 R17
(2520.5 mm), 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).
