I do the same as Becky and have a trashed rear wheel with old tires that I don't want to risk riding outdoors.

If I do for whatever reason use my good tires on the trainer - I make sure to inflate the tire before using the trainer, and to have the trainer tight enough against the tire that there can't be any slippage. The tire doesn't seem to wear as fast that way on the trainer.

Most of my tires end up being ones that come off bonktown - they have the hutchinson equinoxes for about $10 (33 tpi) periodically, which are fine for my commuter bike/surly. That bike is not going to feel like a fast road bike, whatever I do.

Otherwise, I've gotten the continental gp4000 for $18 each on bonktown, the victoria rubino pro for about $20 each and the hutchinson fusion 2 ultras for about $20. All of those are reasonably discounted. I haven't had any problems with quality on any of them, and I wouldn't be too upset if they wore too fast on a trainer. They only let you buy 3 at a time on there, so I usually just get the 3rd as a spare.