Used wheels - corrosion or dried rim tape adhesive? I recently bought some used Fulcrum CPX 4.5 off eBay. They seem to be in pretty good condition, the hub is fine and wheel runs true etc. However, I noticed that when I moved them I heard dust rolling about in the wheels. I pulled of the rim tape for the rear wheel and found loads of white dust (see picture bellow).

Is this corrosion of the wheel, or something else?
Thats just the adhesive from the old rim tape. 

Get a cloth and some rubbing alcohol and rub away, and it should look brand new.