245/70 R17.5 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 - 70 is height of the tyre, which is calculated as 70% of the tyre width (245mm), which means the sidewall height has 171.5 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 mm, which is very similar to 285/35 R19
(2142.88 mm), 225/35 R18
(1931.14 mm), 285/45 R20
(2401.75 mm), 225/50 R16
(1983.6 mm), 295/30 R20
(2151.99 mm), 225/60 R16
(2124.97 mm), 305/25 R20
(2075.02 mm).