You don't have to remove the tire from the rim. But it does take a little effort to mask them properly. Just sand the rim with a fine grit sandpaper. You just want to lightly scuff the rim with the sandpaper, then you mask the tire with tape. Small pieces of tape so youcan keep the mask tight to the rim. Then you paint. Now they probably won't look great for all that long, but I usually only race a set of tires a for few weekends. Then they become warm up tires, then practice tires so they don't have to look pretty for to long.