Okay I was trying to sand wheels to smooth them out but I got a line on the outside of the treads. I don't know if it is Factory defect or if it's something I screwed up. I don't want to do anymore if I'm messing it up. anybody have any advice they are Revell pinewood derby wheels. The tread is smooth just has these bumps or almost air pockets underneath the top layer of plastic. And I think if I send far enough to get rid of them the wheels will be too small her out of limits