Pull the tires and just blast them. You can buy a sandblaster cheap as long as you have an air compressor you good to go. Wear a full face sheild and just use what ever you can get to cover your arms and everywhere else, harbor fright sells glass beads for like 20 bucks for 2.5 gallons, since you don't have a cabinet you'll waste alot so just get baking soda from a pool store or the pool section at walmart. I've also heard of people using sugar, or powdered sugar, salt, etc. Glass leaves a nice uniform color and texture but does cut the metal and leaves little dimples where sand leaves little cuts and scratches, you want something to cut and then go back over to smooth unless your thinking of powdercoating then just pull the tires and have them done. The local price here is about 50 a wheel to clean up and recoat. When you figure the amount of work, paint, clear, materials 200 a set is about the price you'll have in it. Thats almost what all the stuff for my bronze wheels cost and took 3 long days.