Would you trust 13 year old tires?

I sold a set of 4 Pirelli P Zero take offs off my bosses '88 Lambo 25 anniversary model (only other OEM for this tire size was '88 Porsche 911 turbo) and they sold for over $800 bucks on Ebay!!! I about **** my pants during the last minute when they went from $102 to $812 between 3 bidders. They were dry stored since they were replaced with about 200 miles on them, there was still nubs on the outer edges. My boss was going to dump them as they were too old to run (looked fine to me, not even cracks on the sidewall) but I saw value in them as 100 point restoration trailer queen or Museum piece tires so I told him I would "dump them" for him...:) Seems that tire has been out of print for some time and there was one new set left in the USA when I sold them according to Pirelli's web site search. I was poor in high school and ran used tires all the time, I never had a blow out but once on the rear of my 57 Fordor. That was a 2 year old tire too! The suspension was so soft on that heavy car that I didnt even realize I was flat until the back end got a little squirrely on a freeway lane change. I did have one just let go when I was pumping some gas, just a Psssss, then it was flat. Wasnt the tire, it was the stem! it just cracked and blew off.