Agree with Jerry, you have a tire problem.
Ours had what looked like nearly new Wranglers on it when we bought it.
Rotated/balanced the tires as I was seeing a little bit of chopping on the fronts.
Went from no problem to a terrible shimmy at 55. Could drive up to it and through it.
Started looking closer and first off saw the tires were built in 04, and I could see some dry rot between the treads. Jacked the jeep up and spun the tires to find the two now on the front were not round. 1/4" in difference as they spun.
So in trying to fix a problem I ended up creating one.
New BFG Mud Trackers took care of it.
97 Sahara, 74 Renegade, 72 CJ5, 55 Willy's (the Beast) Boss 302, 6:34 gearing, Bose 901 speakers.
God I miss that Jeep. Forgot the kinda Jeep, 80 SX4.