To provide a tandem driving axle requiring no inter-axle differentials.

This tandem driving axle includes a pair of driving axles connected with each other by a through shaft. If the inter-axle differential exists, speed differentiation in the pair of axles is possible. The axle differentiation is required for the reason of fluctuation of distribution of axle load in the pair of the driving axle, for instance. By measuring and monitoring wheel speed and/or tire pressure, a difference of a tire rotating radius is determined and tire pressure can be properly adjusted to impart a common tire rotating radius range to all the tires. The axle differentiation is not required by adjusting other axle parameters to affect performance of the axles such as a suspension height and weight distribution, in addition to the adjustment of tire pressure.