Two years ago, I replaced the Good Year Eagle GT Plus 4 tires that had been on my Newport since 1994. I replaced them because they no longer had enough tread. No other reason. They were not cracked. They didn't have broken belts, they weren't separating. They rode and drove just fine, no hops, no wobbles. I liked them and was so impressed with them that I tried to order them again, only to be told that they aren't made anymore.
I ended up replacing them with BFG Radial T/As of the same size. I drove my car a total of just over 300 miles that summer. Last summer, I didn't drive my car at all. According to this scaremongering "research", even if I only put 1200 more miles on these tires, I will have to throw them away four years from now.
All of this paranoia about tires started when Ford SUVs were rolling due to faulty Firestone tires blowing out at high speeds. They were not old tires either. They were the tires that Ford had equipped the vehicles with, as I understand it, and was mainly the reason for the introduction of TPMS on newer vehicles.
They, government, the tire manufacturers, etc see everyone who drives a car, truck or SUV as an open wallet on wheels. We exist for them to reach in and repeatedly grab as much money from us as they can. Who exactly is the "tire safety group" and who paid for the study? That would tell us a lot. Was it the tire manufacturers, the NHTSA or some combination of both? We are ever increasingly living in a bullshit world these days. This "research" is part of that BS world and serves two purposes, in my opinion. It gives them yet another way to gouge more money out of those of us who can afford to throw away perfectly good tires, just because of some stupid expiration date and, for those of us who can't afford it, it gives them another way to force more cars off the road.
:rant: There, that's my rant