265/60 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 - 60 is height of the tyre, which is calculated as 60% of the tyre width (265mm), which means the sidewall height has 159 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 165/65 R13
(1711.23 mm), 245/45 R19
(2208.85 mm), 175/55 R15
(1801.7 mm), 245/70 R16
(2354.31 mm), 175/75 R16
(2101.41 mm), 255/40 R17
(1997.42 mm), 185/55 R16
(1916.06 mm).