It's difficult to see clearly on Freud's photos, but on the one from RtR -- I counted 8 trailer axles in length. And it appears there are four sets of duals across, so that would be the same as 16 axles on a "regular" width trailer. Also note that the tires are quite a bit smaller than the drive tires on the semi tractors - and that perhaps means the load-carrying capacity is less than "standard" dual sets.
A common-size dual-wheels axle will be rated for about 16 - 20,000 pounds. 18-wheel semis are limited, by state weight rules, to 80,000 pounds GVW, with about 12,000 on the steer axle and the remaining 68,000 pounds divvied up on the two drives and two trailers. So -- 16 axles at 20,000 pounds each yields a load of somewhere in the 300,000# range. I'm not assessing any load on the tractor tires -- the dolly that carries the load takes most, if not all, of the load - none on the tractors. Note that the pusher tractors even have ballast weights to give 'em more traction.
The tractors probably scale 20 - 24,000# each, and with a few tons of ballast on those back two -- oh, heck, call it a 200-ton GCW (gross combined weight). I wonder how much they have to pay at the toll booths?