99 Super Duty came with Firestones, not a bad tire. Towed good and decent traction for a street tire.
Then I thought I would treat myself to a set of Michelins. Probably the poorest tire for towing I have ever had. In 30 years of towing travel trailers. I have never needed a sway bar until I bought the Michelins. The Michelins were just dangerous. Even squirrelly when not towing. Readjusted the hitch, stiffer equalizer bars, added a sway bar, max inflation and they were OK. The minute I could justify replacing them they were gone. Have had many sets on my cars but that was the last set on my truck. Tracked the problem down to a very flexible sidewall when compared to other truck tires and a phenomenon called squiggle.
115,00 on the truck and currently running Toyos. Much stiffer sidewall and a good truck tire. Looking back the stock Firestones were the best tires I have had on this truck for stability and comfort while towing.