bike spare parts--where to buy cheap?

My son is looking for old bike tires. I don't want to destroy a used bike just for this. Any ideas where someone might have old rims/wheels lying around?

Thank you!

sometimes there are old bikes at the South Orange DPW...  you might just stop by Highgear (you could dumpster dive of course, if so inclined).... and ask.  They're a great group of people there and really helpful.

I have a whole bunch of bike parts, though I'm not in NJ any more. A dropoff might be possible to arrange. My email is noglider@pobox.com

There is also the Boys and Girls Club of Newark Bicycle Exchange.