I have a set of tubes, and tires, that came originally on a 84 Fuji Club I bought with less then 5 miles on it about 3 months ago, and the tires and tubes are still on the bike, and I rode it just last week with the original tires and tubes! I've been riding it for a little bit and haven't had any issues with the tubes or tires and there are no cracks on the tires.

Odd thing was, I bought a 88 Miyata 712 last fall, it to had the original tires and tubes, the tires were cracked badly, but the tubes were fine...that is until one of the tubes blew out of the front tire due to a severely cracked tire.

Not sure why two bikes, the Fuji stored in a attic, and the Miyata stored in a garage, both stored since almost new (very little wear on the tread, the Fuji tires still had the nubs) had such different tire life.