10 year old tires ok for highway driving?

I had original Load Range E tires on my 2004 dually and use it only on the highways to go racing. About 1 1/2 years ago, with the tires about 5 years old, I popped a front with still a decent amount of tread on it because it seperated. I put my never used spare on the front after replacing ALL of the rest. Well, that "new", original spare started coming apart a couple months ago - almost 6 years old.

Had a brand new, never used Load range E trailer tire. It was about 8 years old when I finally used it. Tread came off within 2,000 miles!

I'm convinced that after 5 years, your tires are a surprise waiting to happen no matter how they look! Local driving, maybe. Highway, NO!