I have a fifth wheel with Goodyear G614 G rated tires. They still have very good tread and still look good but they were made in the 19th week of 2014. I read that you can go between 6 to ten years....
I’ve never blown a tire but I change tires 5-6 years and watch the air pressure. I’m also careful concerning the brand of tire I buy. Too I store my trailer in an enclosed structure. Keeping tires out of sunlight helps a lot.