My last set of M&H tires was about 20 years ago. They now say to junk all tires (bias ply, radial) more than 6 years old. There is a date code on all tires. I have a set of 40 yr old snow tires on my Olds 442 ... but I'd never use them other than to hold the car off the ground
If
you are wondering if they might be dangerous - do
not drive on them. If you have no confidence in your tires, you are just waiting for an accident.
Why would anyone want to use 40 yr old technology other than for strict originality? I have a friend with a 1963 Galaxie, and he has the original set of tires on the car. I will not even go for a ride in his car, especially since he is about 75 yrs old, is a terrible driver and has had 2 heart attacks.
That is not a bet I want to take.