155/60 R15 doesn't belong to the most popular dimensions for tyres - there are tyre models available, which can be compared to 325/30 R21, 155/65 R13, 155/65 R14. Let's break down the sizing - 60 is height of the tyre, which is calculated as 60% of the tyre width (155mm), which means the sidewall height has 93 mm. The wheel diameter is R15, which means it fits to a 15 inch/381mm diameter wheel. The total circumference of the tyre is mm, which is very similar to 235/60 R17(2242.47 mm), 155/65 R13(1670.38 mm), 245/30 R20(2057.74 mm), 160/60 R18(2039.52 mm), 245/40 R20(2211.68 mm), 165/70 R14(1842.86 mm), 245/50 R20(2365.62 mm).