AFAIK
modern tires have a short life, maybe 5 years.
I have a set of BFG, 205R15, on one of the Avantis, maybe 12 years old, always in garage, they have cracked sidewalls. I also have a set of Coker Bias tires, 6.70x15. They are about the same age and still look good.
Bought some Coker American Classic, 670R15, last year. Too soon to tell how they hold up.