I have been delivering pizza with 2 wheel drive F150s for 3 years now. The worst part is the eating of front tires like a shreading machine. I drive 25,000 a year, about 15,000 of that is delivery mostly in town. With bad ball joints it can eat up a front tire in 3-4 months. With new ball joints it really isn't much better. I don't go fast around corners and avoid doing U-turns, which has helped a little. I do know this is a common problem with the 80-probably 96. What I have been told to help the problem is to have good ball joints, tie rods etc, plus have good shocks. I don't think there is any Ackerman designed into the steering of the 80-86s. Acherman is where the design of the steering makes the inside turning tire turn sharper than the outside turning tire so they follow their circles better. The inside tire takes a smaller circle arc than the outside one as most of us would know. My idea is to make a custom pitman arm and custom tie rods, possibly sourced from racing components. I wish I had a graphics program to draw and post this on here but here I will describe it the best I can.
"V" shaped pitman arm, with the 2 arms of the V separated by their drop height. On the truck, looking foreward, the right-lower section of the V-pitman arm has an attachment point for a tie rod to go to the left front tire,,, the left-higher section of the V-pitman arm has an attachment point for a tie rod that goes to the right front tire. This would be done, ditching the existing tie rod setup and using one piece tie rods going to each wheel. If you can't follow this, draw it on paper in 3 different positions, straight ahead, full left, full right. As the pitman arm turns to full left, the arc of the attaching point reduces the travel of the tie rod and the turning angle of the tire. I hope at least a few of you can follow my description. I would pursue manufacturing of this but have too many health problems right now. I do have a friend who is a semi-retired machinest and he possibley could make this custom pitman arm for me. I would have to go looking for tie rods to do this with. In the long run this could save me $$$ from tires getting wasted. This might work also with the 4wd trucks too.

 

Have you checked all your other front end components? Thinks like radius arm bushings, aliginment, etc? Do you also regularly grease your tie rod ends and ball joints? Are you installing good quality parts when replacing them? Most people go for the 20 dollar ball joint...stay away from those. They use a nylon cup inside, that wears way faster than the better quality units do. What you might save on parts price, you'll end up shelling out in labour and parts the second time around to have the same job done in roughly half, or less than half the time. Rotating your tires might also pro-long this effect. (move them front to back, keeping them on the same side of the truck, switching front left to rear left sorta deal. The old method of front right to rear left, etc was only for bias ply tires.) I'm also curious, are you running P rated tires, or L/T rated tires? The L/T's will have a harder rubber compound, and may stand up better than the P rated(passenger vs light truck)tires will. Running an aggressive grip on the front end will also show increased tire wear, as the deeper lugs tend to fight back a fair bit more than a more steering oriented tire will.

 

you have a high milage ford with bad radius arms bushings and/or I-beam bushings.

there is nothing "Wrong" with the design, its just worn.

 

Find out exactly how your tires are wearing, and if you have modified the truck lowerd it, raisedit, or put more or less wheight on it from the factory then you are in need of an alignment, even if you didn't do any of that stuff, and it has just been a while from your last alignment get another one done. My dad's 97 f350 was originally a typical truck, but then the cattering box was put on and because of the added wheight it offsets the front end so it needed an alignment. From the sounds of it you have had the balljoints, or tierods replaced then that could be your problem. When you replace that stuff you may offset your front end by the slightest amount, but it is enough to do some damage. No matter how good you are, nobody can put a new tie rod on a vehicle and still have an exact alignment