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 180/65 R16(2011.88 mm), 255/40 R21(2316.61 mm), 185/65 R14(1872.7 mm), 255/55 R19(2397.35 mm), 195/40 R17(1846.63 mm), 255/70 R18(2557.88 mm), 195/60 R14(1852.28 mm).