An air suspension system of a tandem axle assembly for a trailer includes a front axle air spring configured to be coupled to a front axle assembly of the tandem axle assembly and a rear axle air spring configured to be coupled to a rear axle assembly of the tandem axle assembly. The air suspension system further includes an air reservoir in fluid communication with the front axle air spring and the rear axle air spring and a ratio valve in fluid communication with the air reservoir, the front axle air spring, and the rear axle air spring. The ratio valve is positioned between the air reservoir and the front axle air spring. Further, the ratio valve is selectively operable to send a lesser amount of air from the air reservoir to the front axle air spring than to the rear axle air spring.