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 265/35 R22
(2338.29 mm), 195/75 R16
(2195.66 mm), 265/50 R19
(2348.65 mm), 205/50 R15
(1840.97 mm), 265/70 R17
(2522.07 mm), 205/60 R16
(2049.58 mm), 275/35 R21
(2280.48 mm).