They seem much closer to omniwheels, and largely inferior for the mecanum's actual purpose: if you check out youtube videos, mecanum-equipped heavy lifters (e.g. KUKAs on the A380's assembly line) are way more reactive, fast and flexible despite being humongous.
Is it just me, or do the physics of the tire not make sense here? I'm clearly missing something, given that they have a working demo.
But it seems to me that the surface area of the tire is getting stretched and squashed as it spins horizontally.
Yep you are correct. It seems like the tires would have to consist entirely of a fairly elastic material, preventing the use of banded or radial designs.