There are few reasons but they aren't IROKs they are grooved SXs.
The old tires and wheels are:
Heavy due to extra wide steel wheel, super swamper tire, weld on bead locks, and the associated hardware (28-32 bolts washers and nuts).
Pretty wore out over all lots of side wall cuts and scars, quickly fading tread due to long burns in the rocks hunting for traction (yeah I saw that video Cory
The groove job is very inconsistent or incomplete cant tell which.
There is no way they'll get inspected.
The good stuff is there bead locks and swampers. They aren't going anywhere permanently just into storage for now unless someone really wants them and makes a really offer.
Since this will be a multi purpose vehicle not just a trail only jeep MTRs are far better all around tire and on a 8" wheel I little less likely to dismount. I ran a similar setup for years and never lost a bead. Ideally I would run alloy wheels but these will work for now. I usually only air down to around 10lbs to maintain tire diameter and it seems to suite my driving style well. I loved every MTR I've ever owned. Believe me when I say this is a thought out decision based on lots of seat through many types of terrain and road time.