Check your wheel bearing/hub assemblies. I had the same issue and it was my driver side wheel bearing/hub assembly. Also, the bald tire or one of the other tires will cause this, a bent wheel could as well. I had a front wheel bent terribly and have no idea how it happened, I didn't hit anything or do anything drastic but sometimes it doesn't take much- this was a high quality aluminum wheel and I was shocked to see it bent, but it was!
Check the wheel bearings first by jacking it up and seeing if you have play in your wheel when pushing on it at the top and pulling on the bottom of your tire at the same time- if it moves back and forth that's most likely the wheel bearing which is in the hub assembly, a simple fix as I'm sure you're familiar with it after all you've done to your truck, and they're inexpensive as well.
***If you have your stock wheels & tires or access to a set from a friend or family member, neighbor, friend of a friend or whoever you know with a similar Ford Truck or Full Size SUV then I'd highly reccomemd swapping out your wheels and tires with a stock set and going for a test drive to see what you can gather- this is how I found out about my wheel being bent. Any Ford Truck Or Expedition, Etc. With The Same Bolt Pattern Will Work To Test Drive Yours & Observe it to see if your issue goes away.
Try these and I'd bet this will help narrow it down so that you can fix the issue. Also, once you fix it, find an of road ahopborvhighbend alignment shop to get everything lined up to eliminate the tire wear issue. Wheel Bearings, Shocks, Bushings, Etc. Will Cause Those Tire Problems, along with other things, you'll get it from here I'm sure. Best of luck and see the picture below my friend!