My 2005 Ford Explorer Sport Trac wobbles from 55-60 mph, I changed all four tires and it felt slightly worse, they balanced the tires but I went to kost and they rebalanced the front tires and charged me 40 bucks, said that was the problem but it still wobbles but steering wheel does not wobble at all
Bad wheel bearings. Common issue with Explorers. https://repairpal.com/bearings-boots-wheel-assembly-studs-956
If you want to be sure before taking it into the mechanic, just jack it up enough to get the tire off the ground (E-Brake on), then try to wiggle the tire back and fourth. Tires should be solid with no movement. If there is some free play, then you know it's a bearing.
Just Google "bad wheel bearing" for more information.