no usually out of balance tires or bent rims will cause a shimmy between speeds ,in your case between 55 and 60. if it has a violent wobble when you hit a pot hole it is most likely the steering stabilizer, i dont think the newer style track bars wear that bad to caus that wobble . and if it is constant it is most likely a universal/ or cv joint on the driveshaft. whichever yours has. out of balance tires or a bent rim is most likely your problem.

out of all the jeeps in this town the d**n gremlin had to invade mine

I've done so much,with so little for so long i can practicly do anything with nothing