....
Think about this: I can over or under inflate my tires easily by a
factor of two (or more) without the wheel's bead hitting bottom. The
vehicle's weight didn't change by a factor of two.
Neither their theories nor their tires hold any air.
...
Ok, now you think about it some more. The pressure of the
tire surfaces against the road isn't uniform as long as the tire
remains effectively round. It's higher near the center of the
footprint, and close to zero at the edge where the tire is
barely touching the road. Deflate the tire, and as the tire
squishes flatter, the pressure becomes more uniform over
an area that hasn't increased a great deal. Deflate the
tire enough, and the wheel has to bring the interior
surfaces of the tire into contact, making the air pressure
suddenly much less significant (the structure of the tire
always supports some weight, just not much relatively
speaking). With inflated tires, just about the only thing
holding the car up is the air pressure (which of course
has to measured while it's holding the car up, and which
of course is strictly uniform inside the tire).
Overinflating by a factor of more than two eventually
leads to the spectacular result I saw in an airline
landing gear tire test. If you're not damaged that much
by flying rubber, you'll now see the car sitting on its rims.
Which will support all its weight. And may need
replacing, along with other structures.