Owners/service Manual problems of the 2011 Ford F-250

Death rumble: after any new set of tires gets about 15,000 -20,000 miles on them, the infamous "death rumble" occurs on this model truck. When traveling at speeds of 60 or more and you turn or hit a bump, the front end of the vehicle starts shaking and vibrating violently. You have to come to an almost immediate stop in order to get the vehicle to stop the shaking. It is so bad that you cannot control steering at times and is even visible to others not in the vehicle. All Ford dealers that I have spoken with about this are aware of the issue but blame it on tires or tire pressure. I have tried several types of tires (as I know have over 125,000 miles on my truck) and always inflate them as per my owner's manual. . . This does not help. . . Nor does rotating, balancing, checking brakes, ball joints, suspension, etc. You can watch many many videos of this problem of youtube and other locations, see write-ups in magazines, and as I said, dealers even know about this issue. . . So why is it not getting corrected???.