Tire age

I've changed thousands of tires in my life and seen lots of instances where the inside of the tire had deteriorated to the point where there were loose chunks of rubber inside. Most of those were in the days before tires got a born on date, and most likely due to underinflation. I've used tires that were really old when I was young and couldn't afford to buy new, I used whatever I could find. I had a set of Uniroyal radial tires when I was about 17 on a full size Pontiac. That was around 1980, and there were known issues with Uniroyal tires, but I put them on anyway. Sure enough, within 2 weeks, the tread peeled off of the face of one tire, then another. I quickly junked them and scrounged up another set of bias ply tires.

My 1976 Pontiac Ventura still has it's original spare tire, A B.F. Goodrich radial that has never been used. The tires on the car are Hankook radials with less than 10k miles on them, but they are now 9 years old, tons of tread left, but I do intend to replace them by next summer, possibly sooner, first need to find 2 more 15 inch rims for it, ditching the 14s.
I also have a set of 4 Michelin TRX metric tires with alloy wheels from an 80s fox body Mustang sitting in my basement. They would be fine for a static museum display or show, but at possibly 40 years old they would not be useable on the highway, I did run them for one day about 12 years ago for a car show and was surprised at how well they still performed.

Unfortunately, far too many people still look at tread depth as the only determining factor when deciding to buy new tires, including some of my own family members. SMH

I generally run all of my cars at 35 psi front and rear, and light trucks at 44 psi.