Will Adding a Flex Air Pin Box Increase the Pin Weight on a 5th Wheel Trailer

Updated 02/19/2016 | Published 02/18/2016

Question:

Ok. Maybe Im looking too much into this. This looks like a great enhancement but have a potential problem. Dry weight / factory stance with nothing loaded of my rig 2013 Sunnybrook Remington 325DB is 9320lb with hitch weight of 1820lb by my calculation King Pin weight is 19.52. Currently loaded now with minimal items I had it weighed and now comes in at 10,300lb with hitch weight of 2160lb by my caluclation King Pin weight is 20.97. So I am really interested in this LC328492 product but if I have done my research this will add about 200lb dircetly to the King Pin weight which would take it to almost 23. However, thinking about this design, I would think that this is strictly a hitch / towing enhancement and the weight on the pin box flanges is uncahnged the two brackets the Flexair bolts to. While I am not an engineer, the weight that the bolts hold regardless of either hitch that is bolted to the pin box flanges are the same. So, do I have to include the extra weight of this hitch into factoring king pin weight? If so I may be in trouble. My research has told me that industry standard for king pin weightof fifth wheels should be 15-25 with most around 20 if you disagree please advise. If I add this enhancement to my rig and must be factored in as official king pin weightinch I will be pushing 23 and I am then getting extremely uncomfortable about that number considering I am slightly uncomfortable as things stand now. Can someone please help me with a little clarification? Any information would be greatly appreciated.

asked by: Kurtis Z

Expert Reply:

No, you would not HAVE to factor in the weight difference between the Flex Air pin box # LC328492 and the factory pin box though you can if you want to and it would be more accurate. But a weight difference of around 100 pounds is not significant in 5th wheel towing (the standard Lippert 1621 pin box is about 100 pounds and the Flex Air is a little over 200 itself).

I don't disagree with your pin weight assessment except that the trailer manufacturers will say what it should be. That usually is around 20 percent of the gross trailer weight but not always so it isn't a hard and fast rule for all 5th wheel trailers.

You can reduce the pin weight some by moving some weight further to the back of the trailer if possible. And if the hitch you have and the truck can handle the 2,160 pounds (or whatever it ends up being) then I would not be worried if it were me.

expert reply by: Michael H