145/65 R15 doesn't belong to the most popular dimensions for summer 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 - 65 is height of the tyre, which is calculated as 65% of the tyre width (145mm), which means the sidewall height has 94.25 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 255/40 R18(2077.22 mm), 185/60 R14(1814.58 mm), 255/50 R19(2317.24 mm), 185/80 R14(2047.06 mm), 255/65 R17(2397.98 mm), 195/55 R15(1870.82 mm), 265/35 R18(2019.1 mm). There are multiple speed indexes available for summer tyres in 145/65 R15: H(210km/h), T(190km/h). The same goes for weight indexes: 72.