Attention: TDR Forum Junkies hammersley said:
Not exactly: You'd still be limited by (1) your GAWRs, (2) your tires' load ratings, (3) your truck's GVWR, and (4) your hitch's capacity.
(1) The Gross Axle Weight Rating [GAWR] of each axle had best not be exceeded if you want to avoid a citation (at best) or a costly replacement/accident.
(2) The Load Rating of each tire and best not be exceeded, either, for the same reason as (1).
(3) The truck's Gross Vehicle Weight Rating [GVWR] can, actually, be the biggest problem since, with a gooseneck or fifth-wheel hitch, approximately 20% of the total weight of the trailer (if not more) is being carried by the truck. "Pin Weight" it's called and is not light. For example, the 3rd Gen 3500 is claimed, by DC, to have a payload of ~4,000 lbs and a GVWR of 12,000 lbs. which, by the 20% rule, would set a limit of a 20K trailer (GN or 5er) - which would still be too low for one of the larger Tetons or Kountry Aires. At 25% "pin weight" the limit would drop to 16K: about that of an Alfa Gold or King of the Road. [Always use the trailer's GVWR for your figures since, you'll find, it's hard to not load one to the limit.
](4) The usual rating for a gooseneck hitch is 25K lbs. , fifth-wheel hitches run from 14K to 30K, and reciever hitches usually top out around 12K. That's Total Trailer Weight. [Yeah, I know: people have been known to exceed these limits by an order of magnitude but, when the badge-toter's looking for an opportunity to issue a citation, it's best to be within the limits.
]So much for the legalities - now for the practicalities:
A sagging set of rear springs is bound to attract Official Notice - and there may be a local ordinance that they might hit you with.
Will your truck have enough power to climb hills while pulling a heavy trailer? Only YOU really know the answer to that one.
Will your truck's driveline stand up for that kind of abuse? Remember: it's a lot more than just than that Cummins - it's the transmission, differential(s), U-joints, wheel bearings, etc. , that also have to be stout enough to handle the job. Again, you'll have to answer that one: it's your truck!
Finally, are you cautious enough as a driver? That heavy behemoth is going to take a long way to get up to speed and a long way to stop - you'll have to be driving at least a quarter (more likely a half to 3/4) mile ahead to anticipate all of the situations. Again, you'll have to answer that one.
Fortunately, you're the only one that needs to know what your answers are. :-laf
