170/80 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 - 80 is height of the tyre, which is calculated as 80% of the tyre width (170mm), which means the sidewall height has 136 mm. The wheel diameter is R15, which means it fits to a 15 inch/381mm diameter wheel. The total circumference of the tyre is 2051.46 mm, which is very similar to 245/40 R18(2052.09 mm), 285/30 R19(2053.34 mm), 205/60 R16(2049.58 mm), 245/45 R17(2049.26 mm), 225/55 R16(2054.29 mm), 195/70 R15(2054.6 mm), 245/35 R19(2054.92 mm).