205/55 R15 doesn't belong to the most popular dimensions for tyres - there are tyre models available, which can be compared to 325/30 R21, 155/60 R15, 155/65 R13. Let's break down the sizing - 55 is height of the tyre, which is calculated as 55% of the tyre width (205mm), which means the sidewall height has 112.75 mm. The wheel diameter is R15, which means it fits to a 15 inch/381mm diameter wheel. The total circumference of the tyre is mm, which is very similar to 165/80 R13(1866.73 mm), 245/60 R18(2359.96 mm), 175/65 R15(1911.66 mm), 255/35 R19(2076.91 mm), 185/50 R16(1857.94 mm), 255/45 R18(2157.33 mm), 185/65 R15(1952.5 mm).