Originally Posted by irwin
irwin, The event is described as:
Cups or Dips in the tread: WORN PARTS
Cupping (also called dipping or scalloping) is most common on front tires, though rear tires can cup as well. It may be a sign that wheels are out of balance or that suspension or steering system parts are worn out. Many Goodyear retailers can provide expert diagnosis and repair.
When I see the worn parts portion of this description and the condition is ruled out, I will want to look at my towing equipment. Is there a lot of side to side movement between the tow bar's draw bar and the receiver opening. Grab the tow bar and shake it back and forth. Is there at least a 1/4" to 3/8" of play there? This might be too much and an immobilizer might help. The Blue Ox website for description; Dual Immobilizer.