Method for controlling the traction of a pneumatically sprung vehicle and air suspension system for carrying out the method

In a pneumatically sprung vehicle (1) with a front steering axle (A), one rear drive axle (TA) and one trailing axle (SA), traction is controlled by an air suspension system (36), having a "pressure ratio control" mode maintaining a parametrised ratio of air pressures in supporting bellows (2, 4) of the drive axle (TA) compared to air pressures in supporting bellows (3, 5) of the trailing axle (SA); a "relieve loading of trailing axle" mode checking whether relieving of the loading of the trailing axle (SA) is possible without overloading the drive axle (TA); and an "optimum traction" control mode increasing the pressure in the supporting bellows (2, 4) of the drive axle (TA) and reducing the pressure in the supporting bellows (3, 5) of the trailing axle (SA) without exceeding the maximum permissible axle load of the drive axle (TA) while maintaining residual pressure of the trailing axle (SA).