It's not quite intuitive, but because the front axle pivots, it can get very dicey quickly. I've known this for years, but have been surprised by it on both my 770 and Kubota. What can happen when you don't have enough ballast is that the rear tires lose contact with the ground. Simple enough, but the tractor is not perfectly balanced side to side, so it will begin to list to the heavier side. It starts slowly, so you are duped into thinking you can control it by dropping the load to the ground or stop moving or whatever. If you are carrying it at 6 inches above the ground, no problem. 3ft = problem. Between your reaction time and drop speed, you don't have the time. Plus, the list seems so slow at first and then speeds up exponentially.