I used to laugh at old tire stories but have had 3 BFG 10.50 x 15 All-Terrains come apart on me at 70 on blacktop. This not only screwed up three different trips but also banged up both front fenders on the 64Dog. I also had an "old but looked good" tire shed its tread on the Interstate at 70. I am now considerably more leery about tread separation and throwing belts. I guess I think that if you use them every so often they will be more apt to last than if they are just sitting for years. But I really don't know. I had a brand new 12.50 x 15 on a 15 x 10 rim that sat for 10+ years off the ground as a spare tire. Tire looked absolutely brand new. I was going to use the vehicle again so aired up the tires to 35 psi. Three days later I looked at the spare and it had blown up. There was a split across the top of the tire and the belt end was protruding through the split. This on a tire that had never been on the ground.
R.