In my Brooklands Gold Portfolio of old Beemer tests they found that unequal loading of the panniers caused a wobble.
Wobbles were much more common 50 years ago when tires had a flatter profile, and I have found the more rounded the tire the more stable my airheads are.
So dont dick around with worn tires / flat profile tires.
Lasertechs or Distanzas both have a good round profile and work well on airheads.
Adelaide Hills, Australia. 93 R100 GS, 77 R75/7 ,70 BSA B44VS, , 86 R80 G/S PD, 95 BMW Funduro F650 ST