IF your truck has a maximum tongue weight number assigned to it it would be without any weight distribution system attached. If you try to figure it WITH the WD in play then you could keep adding spring pressure and pretty much carry ANY sized tongue (but the rear wheels would eventually be clear off of the ground. Their concern is probably NOT the weight on wheels but axles, frame and the receiver itself. The MOST important thing about tongue weight is to remain below the axle ratings AND the GVWR of the truck.