Weight will be the biggest issue. If it were me, I would just make them. The stock PZ wheels that I've seen are just discs of foam with stickers for the hubs. Just find some soft light foam and cut it into small discs the size of the tires you want. Then cut some round dots out of tape or a spare sticker, and put them on the wheels. Either drill them in the center with a tiny bit, or push a hot pin through.
Breaking the gear shouldn't be a concern unless they're really heavy, and the plane probably wont fly then anyway.
