We found a good file for rounding the edges and taking the gator tread or grit off of the surface of the tire is a carbide tile file available at Menards and probably other places. Very similar to what kn7671 has a link to at buckandryan. Some people like to use a diamond sanding pad or plate to put a final finish on the tires and get them to perform like they would after running them for a few minutes and not aggressive like they would be if you just cut them and put them on the track.