245/70 R17.5 doesn't belong to the most popular dimensions for 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 285/30 R19
(2053.34 mm), 215/75 R15
(2210.11 mm), 285/40 R19
(2232.42 mm), 225/40 R19
(2081.62 mm), 285/65 R17
(2520.5 mm), 225/55 R17
(2134.08 mm), 295/35 R21
(2324.46 mm).