235/30 R20 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 - 30 is height of the tyre, which is calculated as 30% of the tyre width (235mm), which means the sidewall height has 70.5 mm. The wheel diameter is R20, which means it fits to a 20 inch/508mm diameter wheel. The total circumference of the tyre is mm, which is very similar to 195/65 R15
(1993.34 mm), 265/40 R21
(2341.74 mm), 200/60 R17
(2110.52 mm), 265/65 R17
(2438.82 mm), 205/55 R15
(1905.38 mm), 275/30 R21
(2194.09 mm), 205/70 R15
(2098.58 mm).
