It's not the tracks that cost you. It's the idlers, sprockets, etc.

My comment was is in response to metal treads causing damage...

It's the pressurized air in the tire that reduces applied ground pressure from the vehicle not just the surface material.

Not sure why you are responding to my comment either... but what you are saying makes no sense to me.

Obviously the pressurised air itself has mass, but I think its more to do with tyre deformation modifying the contact surface area. The air inside is just to distribute the load across the contact area.