I bought a set of used 20" OEM rims today and I found them for a good price but they have some problems. This stuff seems to be at every location a weight was at one time. Is it possible to clean it off? Or did it eat up the aluminum? Can't really tell if it is sitting on top of the rim or if it has eaten the anodize.

 

Take something with a fine point (a pen will work, but if you can find something else with an even smaller point the better) and run it over the area. If it drops down, it corroded/damaged/ect., if it rises, then its something stuck to the wheel.

I'd recommend using something like Goo-Gone to try and remove it, just make sure to clean it off well after your finished.