This is currently the best rated tyre we have and there is a reason for it - it combines sportiness on snow and dry and very good safety margins on the wet. It’s designed to maintain the joy of driving, even on winter tyres, but still manages to be safe at all times. 100% recommended.
255/30 R20 doesn't belong to the most popular dimensions for winter tyres - there are 3 tyre models available, which can be compared to 155/60 R15, 170/60 R17, 160/60 R14. Let's break down the sizing - 30 is height of the tyre, which is calculated as 30% of the tyre width (255mm), which means the sidewall height has 76.5 mm. The wheel diameter is R20, which means it fits to a 20 inch/508mm diameter wheel. The total circumference of the tyre is 2076.59 mm, which is very similar to 255/35 R19(2076.91 mm), 255/40 R18(2077.22 mm), 255/45 R17(2077.54 mm), 215/65 R15(2075.02 mm), 305/25 R20(2075.02 mm), 195/65 R16(2073.14 mm), 225/45 R18(2072.51 mm). There are multiple speed indexes available for winter tyres in 255/30 R20: V(240km/h), W(270km/h). The same goes for weight indexes: 92. You can find 255/30 R20 on 1 car models - mainly Audi.