Yup...spacers have some wiggle room, thus a hub-centric ring would ensure all is properly centred. You can get crap behind the spacer too that will not allow it to seat flush on the hub. A steel hub vs. aluminum spacer = corrosion...the two metals don't get along well.
I was also thinking some sort of steering box/rack/bearing issue too...he said it was in the steering wheel...can't be the tire if he swapped someone's rim and it still does it.
Go over all bolts and re-tighten to spec?
Frustrating I'm sure.
