If the shocks are really shot, you can actually get a tire that will not settle from a bump and continues to "hop" down the road. This will cause cupping and other wear problems. Coil suspensions are more prone to it, in particular I've seen full-size vans with a tire hopping on a smooth stretch of highway.
_________________________

Tip: see if your question has already been answered before asking it. Try our handy-dandy search tool!