A level selecting unit is a device for selecting a tractive force level from a plurality of levels when a velocity stage of a transmission is a first velocity. The plurality of levels includes at least a first level and a second level. A control unit controls the engine. When the velocity stage of the transmission is the first velocity and the first level is selected, the control unit controls the engine on the basis of a first tractive force characteristic. The first tractive force characteristic prescribes a relationship between the vehicle speed and the tractive force of the vehicle. When the velocity stage of the transmission is the first velocity and the second level is selected, the control unit controls the engine on the basis of a second tractive force characteristic. The tractive force is reduced more in the second tractive force characteristic than in the first tractive force characteristic.