Check with your tire manufacturer.
I change every tire on every vehicle I have at the 6 year mark regardless of tread/ware. (if not before due to tread/ware)
That's what I've read the manufacturers consider the life of the tire.
Therefore I do not cover my tires and just change them out on that schedule,
the bean counters at Michelin, Firestone, etc. know far more about tire aging than I do.
PS I've done that for at least the last 35 years and in that time have not had a blowout, or sudden flat, only an occasional slow leak due to nails.
Lynnsr