A system and method of increasing the traction and mobility of a tandem axled vehicle by disposing an endless track 16 around the vehicle tires 18,20 and using a tensioning device 22 to impart a force on the endless track 16 to maintain an optimal track tension. The tensioning device 22 may impart a constant force, a force within a set range, or a variable force controlled by a processor 64 on the endless track 16. The processor 64 monitors vehicle parameters to determine if endless track slipping is occurring. The slip-control processor 64 sends signals to the tension device 22 to increase endless track tension when a track slip condition is sensed, and sends signals to decrease endless track tension when slipping is not occurring, thereby allowing for greater suspension movement and improving overall vehicle mobility.