Pin Weight Calculations

[rbev2308]

First off, I have researched this on various areas of the forum and have a decent grasp of how this works. Looking for some advice. I am upgrading my F-150 to a F350 Diesel (2013, 3:55 gears, 11500 GVWR, RAWR 7000). I know
for a fact the truck weighs 7700 lbs. Empty Rear Axle weight is 3100. Payload consisting of adults and big As* dog (200lbs) puts it at 1,000 lbs, factor in full tank and 200lbs or so on the hitch, I am at approx 8900 lbs (truck had 1/4 tank when weighed). With that, GVWR would probably be reached before RAWR. I have 2600lbs to play with and most of the Fifth Wheels I am looking at come in between 1900-2200 lbs Hitch wt (Empty) or between 18-21% of the total dry weight. My question comes in with respect to the payload of the trailer itself. If it has a capacity of say 2,000 lbs, and you equally balance that load, how does it affect the hitch weight. If the trailers empty hitch weight is 20% of the total dry weight and you add 1,000 lbs, do you add 200 lbs or 20% to that hitch weight? Would not seem logical to say adding half of the cargo weight to the hitch. Yes, the overall weight of the trailer is still within the GCW of both truck and trailer. Just do not want to blow a suspension in my truck. I don't want to "nuke" this math but want to feel comfortable. A Dually is not an option and I would like better understand how pin weight is calculated when adding cargo. I am also mindful of DOT as they may simply look at GVWR of 5th Wheel and truck and if it goes over the GCW, give you a ration of crap. I know this may be an old regurgitated topic that others have had. I honestly understand and buy off on the weights. Just hung up on this pin weight calculation

[JRTJH]

Pin weight is something that can easily vary from person to person even when towing the same fifth wheel. Loading half your cargo behind the axles and half in front will "in theory" keep the pin weight the same. Most RV's don't have convenient storage for payload in areas that would be conducive to loading in that fashion. Rear Kitchen models tend to be "tail heavy" while center kitchen models tend to load much of the cargo over the axles. However, depending on the size of the front cargo storage compartments, one can easily load enough to increase the pin weight much more than expected. With toy haulers, it's very easy to lighten the pin weight too much and reduce the percentage to much less than 15%.

I know this seems to be "talking in circles" but trying to "forcast" pin weight is a difficult task. Most of us can visualize what we think we will load and where we will put it, but when we start loading, things just don't always fit where we expected.

The best I could suggest is to load the way you camp, and on the way to a camping destination, stop by a CAT scale and put some real numbers to your weights. Then you will know whether you're OK or whether you need to rethink what is stored where.

To get some "best guess" numbers, I'd suggest taking the GVW of the trailer, calculate 15% of that as the "low pin weight" and 25% of that as the "heavy pin weight" and expect that your RV "should" come in somewhere between those two numbers. Adjusting the load can help some, but if you're at 15% and too heavy, it's going to be tough to get the numbers right.

[KanTC]

Welcome to the forum rbev2308.

I think you have a very good start on "doing the math & crunching the numbers", but...

Originally Posted by rbev2308

Just hung up on this pin weight calculation

Yep! You're looking for an exact number that's impossible to calculate ahead of time.

As John explained, there are far too many variables involved to predict 'exactly' how much the dry pin
weight will be affected when adding cargo to any given 5th wheel. That's one of the reasons why it's
typically suggested that a buyer "estimate" 20% of the 5th wheel's GVWR to be the loaded pin weight.
Obviously it's not an exact science but... it's about the best we can do prior to purchase.

You've already weighed the truck, calculated your approx available payload, and you know the GVWR & RAWR.
You have the necessary numbers..... so, stop and have fun shopping!

Terri, the Chevy co-pilot

[f6bits]

Your assumption is correct that you should add 20% of your 1,000 lb load to the pin weight. As others said, it's a matter of juggling what you pile on board.

I find that most specs are light on the pin (or hitch) and that loading up your front storage compartment, batteries, and propane will get it closer to proper balance, thus adding closer to 30% of your 1,000 load to the pin weight.