Had a decent looking tire explode in my face as I was pumping it up at less than max PSI. No idea how old it was but probably over 5 years. It was also a Specialized tire but I wouldn't hold either of these instances against them. I have also seen, though not experienced, the separating casing on tires that were likely younger than yours. Who knows how they were stored? I wouldn't trust my well-being to a set of tires that had spent 5 summers in a hot garage.

You made me remember that I have an aging set of back-up tires I should probably give to a non-driving friend down the street who has been riding on knobbies turned slicks for a while.