I would happen to guess they are more expensive new for a couple reasons. The Mog sizes 12.5,14.5 have never been very common for other use.
1200R20 only common use today is forklifts and specialty heavy equipment. I'm pretty sure they are all usa, Canadian manufacture as well. I'm pretty sure you won't find a Michelin 11R24.5 for $300 new.
14&1600r20 had uses for mobile cranes and such for a long time as well as some heavy truck. I wouldn't be surprised if they used odd ball sizes to reduce thievery and such.
One would think that the common sizes for equiptment 17.5R25 and 11R24.5 would be better because they would be easy to source anywhere in a pinch.
It is fairly common to see one ton 16" pickup tires replacing implement and other rolling tires for farm use because they are much easier to source new used and otherwise.
You bring up some good points there, but what I don't get is why people pay more for
used military tires than what new civilian counterparts costs.
That 17.5, 22.5, or 24.5 tires aren't popular for vehicles that go off the beaten path I do understand. With the bead profile they have, they don't stay on the rim any better than the dreaded 16.5s did when run at lower pressures.
But regardless of price, no legitimate tire dealer would sell nine year old tires for a vehicles that potentially could be driven on the road - and they most certainly wouldn't pass them off as new. And no informed consumer would buy them for such use.
I have half a container full of old tires, many of which have little or no miles on them. But I'm not selling them, or giving them, to someone who I even remotely suspect might take them on the road. Instead they slowly but surely get used on trailers and various vehicles I have that stays on the property for the very most part.
On my street driven vehicles (pickups and cars), tires generally get replaced at five years, sometimes six or seven, depending on many factors. They may have 80% tread left, and often 99% (I'm spread between too many vehicles to wear tires out), and then they go into the container. Yep, perfectly good looking tires that I'm not about to let someone else drive on. Or even myself.