michelin website.... Q&A
*What is the expected service life of tires?
**While most tires will need replacement before they achieve 10 years, it is recommended that any tires in service 10 years or more from the date of manufacture, including spare tires, be replaced with new tires as a simple precaution even if such tires appear serviceable and even if they have not reached the legal wear limit.**
I've bought tires for my trucks since the late '50s. Lots of tire brands..... but the last 20 years or so I use mostly Bridgestone P and LT tires on my trucks.