Sometime the tires wil start 'cupping' when there is a wobble issue up front or bad ball joints if ridden on for periods of time before addressing the problem. This slightly alters the actual flatness shape of the tread and will continue to 'shimmy' until rotated to the rear and driven on for a while to get them worn back to a flatter tread. Or replaced. Balancing them does not fix the 'cupping' of the tires shape.

Maybe the tires started cupping when on the front with bad parts and still have a misshape to them Causing the 'shimmy' ? Would not be the first time I Have seen this happen.

 

The death wobble has stopped on my jeep, I welded the insert for the one ton tre onto the pitman arm, got a steel steering box spacer, a steering box brace and adjust the toe.
It is gone for now! Hopefully for good lol

 

Congrats and I hope you don't jinks it.

 

My DW and what I thought was rear DS vibration problems stop immediately after getting rid of my 33'' KM2s.

 

I've heard from several people now, the km2s do not balance well. I still get a tire vibe at 45