From my experience with truck tires at work and personally, I'd say 10 years in there approx life span.

Recently wife drove our durango to Montana 4000 miles round trip on 9 year old tires that had 48K miles on them with about 3/8 thread left. 80mph out there for hours at a time...

She made it out there fine. Checked the oil and air in all four tires before she left MT to come home and made it to Iowa and had the sidewall blow out on her right front. Luckily it happened as she was getting on the highway in the morning as she was leaving the motel. She had a spare on board and we were able to get a road service guy from the area to change it for her on the side of the highway. Tire guy told her the tires were old and that is more likely why it blew.

Police showed up too behind her with his lights on, thank you police for that.

She is not dumb about air pressure as she watched me for years check trailer tires. She checks them each time she walks around the car with her eyes had a tire gauge in the consol she used in MT. her tire was not low, the sidewall gave out from either wear or she hit something on the highway. She says she did not hit anything that she knows of.

I mounted her Goodyears in 2010 that I got from the Tire Rack. The date on the tire is the 42 week of 2008 they were built. They do show some cracking in the sidewall, they are toast at 9 years old.