Likely tire iron damage, as aluminum is pretty soft. When I go over a rim that has damage from improper [use of] tire irons, I smooth out the nicks with a very, very fine abrasive paper. Sorry that I can't recall the equivalent grit size. I have several sheets that I cut into small squares and keep handy. Works well on brass or aluminum, and is only short of a polishing grade. Works very well. I did a set of wheels on a recent flip that had some roughness.