145/65 R15 doesn't belong to the most popular dimensions for allround 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 195/60 R15(1932.08 mm), 265/35 R22(2338.29 mm), 195/75 R16(2195.66 mm), 265/50 R19(2348.65 mm), 205/50 R15(1840.97 mm), 265/70 R17(2522.07 mm), 205/60 R16(2049.58 mm). There are multiple speed indexes available for allround tyres in 145/65 R15: T(190km/h). The same goes for weight indexes: 72.