got a set of 16" wire wheels, and a couple of them need new tubes. I'm curious if I can use motorcycle tubes, or if I have to pay more to get automotive tubes. the tires are 600 16's. obviously I can run downtown to coker tire but it looks like they run 50 a tube. that just seems a bit much. I also have a friend that works at a motorcycle place. probably $10 a tube there. what you think? want to get this thing where it will roll around so I can push it in and play with it now and then. thanks.