295/30 R18 doesn't belong to the most popular dimensions for winter tyres - there are 0 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 (295mm), which means the sidewall height has 88.5 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 1992.4 mm, which is very similar to 225/45 R17
(1992.71 mm), 195/65 R15
(1993.34 mm), 185/75 R14
(1988.94 mm), 175/80 R14
(1996.8 mm), 255/30 R19
(1996.8 mm), 255/35 R18
(1997.11 mm), 170/60 R17
(1997.42 mm).
