Disclaimer: I am not a rubber chemist, but I’ve worked along side some talented ones and have picked up quite a few things. So take what I am about to post with a grain of salt.
Rubber deteriorates over time. I think it is mostly attack by oxygen. Tire manufacturers put antioxidants (AO’s) in the rubber to sacrifice themselves instead of the rubber itself. You can sometimes see these as a rust colored film - although other colors are possible.
There are also waxes embedded in the rubber matrix that form a barrier to slow down the deterioration. You can sometimes see these as a whitish film. Both the AO’s and the waxes flake off as the tire flexes, but the flexing allows the waxes and AO’s to migrate to the surface, replenishing the barrier. Yes, they will eventually be used up.
In a modern steel belted radial tire, it is the rubber around the belt edges that is of most importance. That is the most highly stressed area of the tire. Unfortunately, you can’t see what’s going on in there, so we use cracks on the outside as an indicator.
Unfortunately, some tire manufacturers use certain types of rubbers that are not prone to cracking in their sidewall and that disguises the condition of the internal rubber.
Further, cracking is a combination of the condition of the rubber, and the amount of flexing it has undergone. So tires not frequently used aren’t as likely to be cracked - as is the case here.
Put another way, if a tire is cracked, it should be removed.
Lack of cracks doesn’t mean a tire is good. That’s where the age thing comes in.
I am of the opinion that heat is the major driver of rubber deterioration (Arrhenius’s Rule), so tires in Phoenix don’t last as long as tires in Minneapolis. I think the appropriate age of removal is 6 years and 10 years respectively. Places in between are …… ah …… in between.
If some rubbers aren’t as prone to cracking, why not use those? Because they don’t work well in certain areas of the tire, and the belt edges is one of those.
What about tires dressings? I am of the opinion that they generally cause more harm then good, because many of them remove the wax barrier. The exceptions are those that have antioxidants.
Oh, and avoid using tire dressings that have silicone in them. Every tire slippage problem I investigated involved silicone somewhere. Armorall is one of those (or at least, it used to be!)
Now about those WW2 tires. Those are bias tires and those work differently than modern radial tires. Not only don’t tires from that era perform at the level modern tires do, they would be expensive because of the excessive amount of rubber used in them (which is not to say that heavier modern radial tires are better. It’s a lot more complex than that!)
So to address the OP: Replace those 14 year old tires. You don’t want that car damaged when the tire fails as the usual failure mode involves a large flap of the tread (and top belt) coming partially off and beating the fender to pieces. (see videos of race cars)