10 year old tires ok for highway driving?

Wow, I had a nice set of tires on the rims stored in my garage, stacked, proper air, towel between each tire and armor all'ed down. Went out to the garage to find the top tire seperated just like that picture that has been posted. The tire was right at 12 years old at the time. Since then, I do not store any tires.

My concern are all the spares out there in trunks that have the same risk of seperation. I wonder if any of these temp spares hold up better than a traditional tire.