PeterPan

Please forgive me if this post shows my ignorance. I'm a happy owner of a 2009 Scion XD, have never used my donut tire, and am wondering if I should replace it anyway. I recently pulled the tire out and pumped to to the proper pressure (60 psi) , bounced it a few times, and it seems to be in great shape. But this being 2024, that tire is 15 years old. We're planning one of our trips to mountainous areas this fall, where there is often no cell signal. So if I have a flat, I'm going to need to rely on that donut long enough to get to a repair place. They don't seem to be cheap to replace, so I'd like to know if I am overly paranoid worrying about this "never-used" tire based only on its age. I live in Florida so its never even been exposed to freezing temps, but it does get pretty warm in a locked car in the summer. What is the truth here?