How much air do you have in the tires?
I never had a problem with 35x12.5 tires. I had a set of 38x15.5 15 bias ply bad roads and cattle chutes are not your friend. Death wobble only on solid axle trucks
Take back to dealer have alignment checked.
My wife called my 87 Papa Bronco and my 72 baby Bronco.
So if an 85 is considered full size Bronco and a 2021 is full size because of the Sport where does that leave the early Broncos?
Mechanics don't like when you bring your own parts. It's like bringing a steak to a steakhouse.
Recommend taking it to a shop and have it looked at (hopefully someone you trust). Brake pads are cheap having rotors done price goes up quite a bit. Don't forget that has drums in the back.