78w72
I have three collector cars too. I didn't mention the tires for the '49 Caddy Limo - didn't think you'd be interested in 750x16" wide whitewalls...
Part of the problem with my redline Uniroyal's is that they sat in the dealer's warehouse for years before I bought them. Tires start aging the day they leave the factory, not when they're mounted.
FWIW - I never recommended changing tires every 5 years.
My last tire replacement was the GTO and the Camaro at the same time. Was it a large expense? Not as much as a 5 spd overdrive transmission and a very small fraction of what I have in the cars. To me it's just part of the deal with owning old cars.
The GTO gets driven the most, but tire changes are done by age, not by miles driven.