Like a lot of guys have said, there's no reason to run off new people. I think that the rules are there for a very good reason, but you have to cut people some slack when they first show up. That's the sort of thing that keeps people involved.
As far as the tires, on carpet they last a really long time. In fact, when they start going bald the cars usually want to start traction rolling. So guys out here save them for asphalt, where they are perfect. Asphalt is a lot harder on tires, so it's pretty much a run them till they explode thing. For the most part, the tire deal takes care of itself.
That being said, a ground down tire is fairly obvious, since tires that are worn out will usually be softer due to tire sauce, and the "wear" factor is much different than a ground tire.