195/45 R15 doesn't belong to the most popular dimensions for allround 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 - 45 is height of the tyre, which is calculated as 45% of the tyre width (195mm), which means the sidewall height has 87.75 mm. The wheel diameter is R15, which means it fits to a 15 inch/381mm diameter wheel. The total circumference of the tyre is 1748.3 mm, which is very similar to 155/65 R14(1750.18 mm), 175/65 R13(1752.07 mm), 185/55 R14(1756.46 mm), 165/60 R14(1739.19 mm), 165/70 R13(1763.06 mm), 160/60 R14(1720.34 mm), 175/60 R14(1776.88 mm).