This is the first I've heard of stretching a tire with a bead. The bike was stored upside down with the tires deflated for the past year. Perhaps the rubber shrunk and will stretch somewhat now that they're inflated?All
clincher tires have beads, whether wire, kevlar, or other material. The strength of the tire is not in the rubber itself, which is why I don't concern myself with any age-related apparent problems with the rubber (cracking, etc.), and have never had any resulting problems in the 200 or so tires I have bought and maintained over the years for myself and my family. In fact, all of the serious problems we've had with tires were with ones that were new or nearly new, meaning there was a manufacturing defect. If they make it past the first few hundred miles, we wear them out down to the strings. If a tire gets a cut, we boot it and put on another thousand miles or two or however many it takes to finish wearing out the tire. Those have never been a problem, and we've probably ridden 50,000 miles on booted tires that other people would have thrown out in fear of the unknown.
The worst problem I've had with getting tires off and on was when our tandem's original rim strips were splitting at the spoke holes from the pressure so I added a cloth tape rim strip over the originals. I wasn't able to get the same tires back on after that, so I had to remove both rim strips and put only the cloth one back on. Tire liners didn't affect the difficulty in installing or removing tires. Some tire-and-rim combinations are more difficult than others. Briefly explaining why, in text, is not easy, but has to do not just with the outer diameter of the rim but also with the depth of the rim between the bead seats. Even a larger-diameter rim won't be that hard if it has a deep area between the two sides' bead seats. The two layers of rim strips above effectively made for a larger diameter between the bead seats.
I can usually do it by hand though. With the air out of the tire, I push the valve toward the tread so the bead can go farther down in around the valve, then stretch the tire to the side opposite the valve so it kind of bulges there, then pull it off. To put it back on, I put the valve side in first (one bead at a time), and again stretch it toward the other side so it will go over the rim, finishing oposite the valve, then pulling the valve farther through the hole and towards the hub. I worked at a bike shop for a few years in the late 1970's and installed and removed thousands of tires.