Thumping noise coming from rear
 

Recently purchased a 99 MGM with 66K miles. Developed a thumping noise which sounded like it was coming from the passanger side rear tire.
Immediately replaced all 4 tires but noise prevails. Car sounds like an uneven load of laundry when moving. Noise get more pronounced on left turns which load right tire and less pronounced when making right turns. Any ideas would be helpful and much apprieciated