rpeters549· Oh - THAT guy...
Much of age damage is NOT visible to the naked eye. Many people run 20 year old tires dozens of times and never have an issue. I have personal experience through me or family/fiends with at least 6 tire failures due to age. You do not know all the history of the tire since it is new to you (was it run low pressure before you owned it, road hazard damage internally, etc) so it is a gamble. Ride them all you want, but if it was my bike I would replace them sooner rather than later. But then, I prefer to spend a little money now and not roll those particular dice with my life.