This thread reminded me of Jay Leno's piece in Hagerty from over the summer:
https://www.hagerty.com/media/opinio...ut-1200-tires/
Indeed, a number of factors come into play with how long tires may last (quality, exposure to UV, driving habits, general road conditions, climate, storage, care, etc.).
In 2005, I purchased a set of Diamondback radials for my '63 Bonneville. The car was in the shop at the time for a frame swap, and stayed there, out of the sun and off the road, until this past November. These tires look and feel like brand new. Surely, the rubber itself has aged somewhat, but not to the extent it would have had the car been driven (at all) or left standing outside in the daytime exposed to UV. (So far, they have a grand total of about 150 miles on them.)
My daily driver is a 2006 Cadillac STS-V. These cars came from the factory with Pirelli run flats which everyone hated. When I got my car in 2021, it already had Continental Extreme Contacts on it. These are amazingly soft riding tires (not run flats) with excellent grip and handling characteristics. However, I've had to replace every tire on the car for various reasons, despite them all being relatively new when I got the car (sidewall separation, sidewall damage from a nail - yeah, just past the tread line - etc.). I'm in the northeast, so winter weather is a factor. I keep them inflated to about 36psi (air, not nitrogen, so they do expand and contract). I don't expect these tires to last 5 years, even if I were to reduce the miles I put on the car every year.
In short, any of these "tire life guidelines" are simply that: guidelines. Every model of tire is different, every car is different, every road is different, batches of tires are different, UV exposure differs...there are just so many factors to consider that at some point, personal preference and experience has to be taken into consideration.
I will be driving on my Diamondbacks on the Bonneville to Arkansas from New York this year, and I have no concerns about the drive. (Prior to this set of tires from 2005, my Sears GR78-14's dated back to about 1977, and served me well - LOL.)