Back when I was rolling in my D-250 and had to spend a fair amount of time on dusty country roads, a drop-off mutt decided to hang out at my place for a few months. When I found him, he was hiding under the back of this old diesel Dodge, and during the heat of the day, he'd take his siestas under the back of that dusty buggy til dinner was served...he started to listen when I began calling him Dodger, and trained him to do a few things to act civilized, like not bite my hand when I tried to feed him (he had trouble with that skill). That summer of '03 was particularly toasty, so mid-afternoons it was good practice to head for shade and do maintenance chores between fieldwork. One scorching afternoon, I'm taking a water break while servicing one of the tractors, and as I'm kicking back on an upside down 5gal bucket, I hear a KA-BOOM and a huge cloud of dust engulfs the back of that D-250 that was parked about 50 feet away, front half of the truck under a shade tree...Dodger comes stumbling out of that cloud, looking like he was seeing stars, and eventually a purty good sized pot knot swole up on his noggin. Apparently, the 12yr old OE Michelin spare tire separated after that end of the truck had been sitting in the sun for most of the afternoon, stirring up all of the dust under the truck during rapid deflation, and Dodger jumped straight up and bashed his head against the rear axle at the abrupt noise. 💥
Since then, I have replaced tires once they hit the 10yr mark, simply because they do not make tires to last forever. I'll keep old tires on projects just to roll them around, but tires that old tend to fall apart when they exceed walking speed. Any cracking on tubeless tires gets special scrutiny as these are weak spots where a rupture can occur.