I HOPE that we get what you pay for - so that the "better" tires don't need replacing just for the fun of it in 5 years regardless of the mileage on them and regardless of their tread depth.
i.e. How often do big rigs replace their tires and when they do, isn't it often just recapping instead of complete tire replacement?
My 4X4 pickup had the same set of top notch and over-spec'd tires on it for at least 12 years before I replaced them based on tread depth alone, with no cracking or other degradation evident other than just the worn tread.
Heavily loaded tires of really too-small a diameter so heat buildup is excessive may be a reason for internal material breakdown, however. We once had to replace a tire three times returning home from a hot summer camping trip because we were pulling a heavily loaded pop-top with way too small (in diameter) tires on it. IMHO, over-kill on tire ratings and sizes (larger diameter is always better) is the name of the game if you don't want to replace them often. Just "good enough" tires is not the way to go.