Originally Posted by suzukipro

I can report back that the new hubs and wheel nuts solved this problem .

What I found was that the O.D. of the hub thread and the I.D. of the wheel nut each wore enough that it was possible for the threads to skip when tightened up. I noticed this as the wheel nut had a lot more side to side slop (think hula hoop) than the new hub / nut had, but viewed individually they looked fine. Anyway I must have taken my wheels off too many times to clean tires over the course of a year and a half, causing the threads to wear down.