I reckon a steel belted tread is a bit stronger than a bias ply nylon tread. My daughter doesn't drive a whole lot. Her Caravan just last week threw off a chunk of the sidewall of one tire, had bulges in another that was vibrating noticibly. Tire dealer looked at them and said way past useable date. It's the rubber that fails with age, not the plys.
Maybe, but it's well known that steel belted radials don't last anywhere near as long as bias ply tires. It isn't even close.
That doesn't seem to be the case, though. The way the tire is build has a lot to do with how long it will last. Steel belted radials are a short lived say to build a tire. I've dragged home quite a few old cars over the years...those with old radials, even if they don't have any miles on them, need new tires just so I can roll them around the yard. Bias ply, just air them up, they're good. Maybe you could look into the details of how the tires are held together, and see if the rubber to ply bond is as important to the structure of a bias as it is to a steel belted radial.
@blowby your spare was probably in a very tire friendly climate both in the trunk away from sun and the elements to last so long with minimal signs of aging...
Rubber is kind of weird stuff, I've found items just a few years old that are trashed and 75 year old stuff that is perfect, and of course every combination in between. Storage conditions matter a lot, exposure to sunlight or ozone, chemicals, but there's something else going on there too. The military has a pretty good handle on that kind of thing. They can pull stuff out of a Depot that is perfectly serviceable and decades old. Not sure about tires, though. When Gulf War 1.0 kicked off the defense department activated many state national guard units, and deployed them. Like, you know, the trucks actually had to leave the motor pool under their own power. All of them. Uh-oh. Well that was kind of a debacle, because it turns out a lot of those trucks hadn't really moved for some time, despite what the paperwork being sent to higher ups might have claimed. Brand new tires, completely dry rotted.
i put the studded tires on the wifes caravan a few years back . never payed any attention to the date .they were hardly worn . ran about 4 months a yr. in winter . so not much . so we went to wash. state for christmas . just after heading home on the freeway the lft frnt tread departed ,never lost air . but the tread tore out the plastic fender well . which had the main harness leaving the ecm above it . ripped out the harness . had to get towed 500 miles home . insurance totaled it . never ran again . they wouldnt sell it back to me . i thought i might splice the harness .ill never know! hmmmm time to put the studs on her highlander again . how old are those ?
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