Much too heavy for practical use. You'd have to specify what type of trailer you had in mind. As far as all steel construction goes, the only ones you'd find are 53' flatbeds and stepdecks, armoured van trailers (very uncommon, but they are out there), and equipment trailers (RGN lowboys, RGN pontoon trailers, RGN beam trailers, etc.). Weights vary greatly between them.
As for a typical 53' van, the frames are steel, but the floor will be wood (or some use polymer), and the walls will typically be thin aluminum.
Depends on the type and size of the rig, but a typical tractor weighs 15,000# and a 53' enclosed van trailer weighs about 13,000#, for a total of 28,000 lbs. Most US highways have an 80,000 pound weight limit, so the load capacity or maximum net weight of a typical tractor-trailer is 52,000 lbs.
13,000 lbs
is it legal for your load to hang over 45" on a 53' trailer
47000
Assuming you're referring to a 53' semi trailer, 41,000 - 43,000 lbs. for an 80k combination is typical.
Specifics? Tandem, tridem, steel, aluminum, 45', 48', 53'? Generally, you're looking at 15,000 - 19,000 lbs, depending on specifics.
it could hold until it drops
Between 9,000 and 11,000 lbs, generally.
In the vicinity of 11,000 - 13,000 lbs.
It depends on what the empty weight of your combination (tractor plus trailer) is. You're allowed a total weight of 80,000 lbs., so, you subtract the tare weight of your tractor and trailer from 80,000 lbs., and you're left with what you can haul legally.
In the vicinity of 9,000 - 10,000 lbs.. more weight of course if it's a refrigerated and insulated trailer.
13,000 - 15,000 lbs, depending on specifics.