What's the shelf life of tublar tires?
The shelf life is going to be different depending on the quality and composition of the specific tire, and the storage conditions.  In general though, you should be able to see if a tire has gone over or not: if the rubber is still soft and pliable, it should be fine to use.

I'd guess that your tires are still okay, but without seeing the tire i can't give you better than a guess.