Question on rating. . .
On Travel trailers it states tongue weight and Trailer CVW. On a 5th wheel it just list GVW. Is the pin box weight less than the GVW of the trailer? A friend of mine (just bought a bigger trailer) told me the dealer told him he was fine with a 16K 5th wheel hitch on a 18K GVW trailer since the pin box weight was less than the CVW on the trailer. Is this true? Can't find any info on this.
I could be wrong, but here's how I would think about the weight; it's a bit like asking about the GCWR of the tow vehicle. So let's start there.
Looking at 2015 GMC 3500 specs, the truck's GVWR is 11,400. The 5th wheel towing capacity is 17,300. Max payload is 4327.
But the GCWR is not 28,700, the sum of these two. Rather it's 24,500. I believe that's because for a compound rating, you only count the vertical load of the pinbox once; either as part of the truck's GVWR, or as part of the trailer's GVWR.
If I add the truck GVWR of 11,400 to the towing capacity of 17,300, I get 28,700. Then if I take away the 4327 payload, I'm left with 24,373, which is pretty close to the GCWR of 24,500. Don't know if the difference is a tank of fuel, or a rounding up.
So from a truck standpoint, it appears that the specs, by way of the GCWR, account for the division of trailer weight when looking at a compound rating.
From a hitch standpoint, if they come with a GCWR spec, you could follow the same reasoning. But if not, it's unknown whether they spec it the same way as the truck manufacturers. A conservative view would argue that when they say 18,000, they mean that's the max GVWR of the trailer you can tow.
Anyway, that's my thinking on it.
