Heres a little idea I came up with that works pretty well. I had seen a tire scuffing tool advertised a few years back, it was real nice and machined out of aluminum but was around $20 which seemed a bit steep but I still really wanted one. Well I have never seen them in the stores and never got around to ordering one.
A few months ago I was at the Hardware store this great idea hit me like
You will need 2 finish washers 1 bolt and nut. Make sure the bolt fits snug in the hole in the washer so its self centering. I don't know what size washers I bought so just take some tires with you and test fit, they should fit in the tire just like half of a rim on a real tire. I also purchased a smaller set for some other tires I have.
Assemble as shown
mount that baby in a drill ( or I prefer a drill press ) spin it up and apply abrasive
( I use an emery board and some fine sandpaper )
Don't apply too much speed or pressure as the rubber or plastic will melt and if you are doing a treaded tire be careful not to sand off all the tread.
Happy Holidays Everyone!!!!!!