180/55 R18 doesn't belong to the most popular dimensions for winter tyres - there are 4 tyre models available, which can be compared to
155/60 R15,
170/60 R17,
160/60 R14. Let's break down the sizing - 55 is height of the tyre, which is calculated as 55% of the tyre width (180mm), which means the sidewall height has 99 mm. The wheel diameter is R18, which means it fits to a 18 inch/457.2mm diameter wheel. The total circumference of the tyre is 2058.37 mm, which is very similar to 245/30 R20
(2057.74 mm), 295/25 R20
(2059.31 mm), 160/70 R17
(2060.26 mm), 245/35 R19
(2054.92 mm), 195/70 R15
(2054.6 mm), 225/55 R16
(2054.29 mm), 285/35 R18
(2063.08 mm). There are multiple speed indexes available for winter tyres in 180/55 R18: W
(270km/h). The same goes for weight indexes: 74.
