I bought a set of rims for my car a few months ago. Worked out the proper fit (outer diameter= same as stock, correct offset, all that jazz). Got them on, they look sweet, and found no problems when driving (no odd vibrations or anything)

Just a couple of days ago, however, a buddy of mine was driving behind me and noticed the rear driver-side wheel was wobbling a bit (about an inch off center, maybe a bit less). So I got him to take the car around a parking lot, and sure enough, he was right! We took the rim off and put it on a balancer and it was perfectly balanced. But then we noticed BOTH rear wheels wobble a bit! (NOTE: rear brakes are drums, front are discs) The front rims are fine though.

Today my friend called and said it might be the screws holding the drum (or drum cover - not really familiar with drum brakes)in place that is not allowing the rims to mount flush to the surface; the mounting surface on my rims is flat (unlike the stock steelies that have spaces for the screws to fit so that the wheel can mount flush). Anybody else have this problem?

Any suggestions?