325/30 R19 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 - 30 is height of the tyre, which is calculated as 30% of the tyre width (325mm), which means the sidewall height has 97.5 mm. The wheel diameter is R19, which means it fits to a 19 inch/482.6mm diameter wheel. The total circumference of the tyre is mm, which is very similar to 175/65 R15(1911.66 mm), 255/35 R18(1997.11 mm), 185/50 R16(1857.94 mm), 255/45 R17(2077.54 mm), 185/65 R15(1952.5 mm), 255/55 R20(2477.15 mm), 195/45 R15(1748.3 mm).