My Phaeton came with 221/2" wheels when I bought it new but when it came time to change out the tires I changed the wheels to Alcoa's. I went with 4 polished and the 2 inter wheels I installed non polished. I don't think anything is wrong with using the steel wheels on the inside rear wheels but I wanted all aluminum. I took one of the steel wheels and put one of the used tires on and I am able to fit a fully mounted and aired up tire and wheel in the compartment next to my propane tank compartment. I sense changed the tires out again and then changed the spare to the newer aged out tires. I think I am old school but I feel better with a spare tire. I have extra steel wheels that I would gladly give to anyone who needs a spare for their motorhome. I live above Sacramento off highway 50.