265/30 R21 doesn't belong to the most popular dimensions for winter 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 (265mm), which means the sidewall height has 79.5 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 285/30 R19
(2053.34 mm), 215/70 R16
(2222.36 mm), 285/40 R19
(2232.42 mm), 225/40 R18
(2001.82 mm), 285/65 R17
(2520.5 mm), 225/55 R16
(2054.29 mm), 295/35 R21
(2324.46 mm).
