If the tire wear was caused when the tires were on the rear, you've got a structural problem (as in accident damage) because the rear camber is set at the factory and is not adjustable. The front camber can be adjusted with the addition of camber bolts.
Worn wheel bearings can also screw up camber--but they'd have to be plenty worn and they would make lots of noise.
I'm a retired ASE Master/L-1 Technician. I still keep current with the latest automotive technology.
Sounds like the tires may have been on the front and that's where the uneven wear occurred. If that is not the case, best to take it to an alignment shop to see what is going on.
An accident, as mentioned previously, may have bent the axle and would likely require an axle replacement. Any damage to the axle should be quite visible if bad enough to cause tire wear as you have described.
2002 Dodge Grand Caravan Sport
2007 Dodge Grand Caravan SXT
2003 Jeep TJ (Wrangler)
Both TJeepman and RickMN gave sound advice......however I doubt the vehicle was in an accident. The odds of both sides doing the same thing is extremely rare....and would require a very obvious damage to the vehicle.
I'm going to agree with TJeepman's first suggestion. Sounds alot like the tires were rotated and the wear is coming from the front area. This almost always caused by a bad alignment and balancing. Like the man said, go have it checked out and definitely replace the tires.
Have the alignment ck'ed. Chance's are the rear camber to neg or toe. The rear camber and toe can be ajusted, only if you have rear drum brakes. If you have an all wheel drive or disc brakes, you can not adjust the alignment.