Here is the solution, right here. I've seen people using heat guns, scrapers, elbow grease, etc, etc. Not the way. This here is an exponentially easier way to get the stickers off your bus than any other method, and it won't dork up your paint.
SO...you chuck this in a drill, rough up the outside edge surface on a brick, and start peeling off decals. I found an easy way was to start at the top edge of the decal and move the wheel downward, with the wheel turning so as to lift the decal off the surface (against the direction of travel), and continue downward removing a vertical stripe of decal all the way down. Then start again at the top. Keep the speed down, excess speed heats up the rubber and wears out the wheel. Wipe away the residue (eraser shavins) with a dry cloth, then check to see if you need to hit a few spots again.
IF you have a sticker with a hard outer skin, like some of the reflective tapes, a heat gun and scraper will remove the skin, then the wheel will take the adhesive.