What is Really the Right Way To Determine Max Payload and Towing Weight?

[Redfour5]

I always like to say: if you need a calculator to see if you're still within bounds on your truck, then your truck isn't big enough. My personal limit is 8000 pounds and < 25 feet for a 1500 regardless of specs, many will feel that is far too conservative but they make 2500's for a reason. If it's a one time pull and you already have the truck, fine, do the math and see if you can make it work, but if you're pulling your TT on vacation and want to see what you can "get away with", just get a bigger truck.

I'm under 7K and around 28 feet as a max (actual 27' 3" and 800 lb tongue...

 

[DavidNJ]

Awesome analysis, my only question is what about the frame? Apparently Ford has a slightly thicker frame on its max payload F-150’s. My big horn has a decent 1546 pound payload but for what I want to do ( camper with 4 people and gear in truck ) if I could safely operate with a 7500-8000GVWR I would be much happier. I will be adding a stronger rear sway bar and the Airlift 1000HD springs for the added payload. My non-LT tires have the load capacity for over 5000 but I’ll probably try to keep the rear axle weight under 4500 pounds. Is there any concern with the frame? Mines a crew cab 6’ 4 Bed so long wheelbase.

There are two things that are different: stiffness and strength. Current frames are made of advanced steels that have pretty high yield points and they are hydroformed which allows shapes, FEA designed, that can be pretty stiff with less weight. Think of the stiffness a bead adds to a flat metal panel. If you are under GVCW you probably have a pretty good cushion before the frame is an issue.

The place you might run into an issue is the differential. Might is the key word here. The bigger trucks have bigger differentials with bigger teeth. Ford 9" are used in some high performance off-road applications, but those often are bigger than 9" and have more meat on the the ring gear. The 9" and the GM 14" also have removable pinion carriers and the pinion has a support bearing on both sides. On top of that, some of these have a brass bold that limits ring gear deflection. These differentials don't have any of that.

Compared to the 2500/3500 differentials (the same on both), the 1500 differential looks like it came from a passenger car.

Net: If under GCVW it should be hard to have a frame issue and unlikely a differential issue. The big issue is having the tires and springs for the payload.

 

[Nsleone]

There are two things that are different: stiffness and strength. Current frames are made of advanced steels that have pretty high yield points and they are hydroformed which allows shapes, FEA designed, that can be pretty stiff with less weight. Think of the stiffness a bead adds to a flat metal panel. If you are under GVCW you probably have a pretty good cushion before the frame is an issue.

The place you might run into an issue is the differential. Might is the key word here. The bigger trucks have bigger differentials with bigger teeth. Ford 9" are used in some high performance off-road applications, but those often are bigger than 9" and have more meat on the the ring gear. The 9" and the GM 14" also have removable pinion carriers and the pinion has a support bearing on both sides. On top of that, some of these have a brass bold that limits ring gear deflection. These differentials don't have any of that.

Compared to the 2500/3500 differentials (the same on both), the 1500 differential looks like it came from a passenger car.

Net: If under GCVW it should be hard to have a frame issue and unlikely a differential issue. The big issue is having the tires and springs for the payload.

That certainly makes sense as to why the only difference for the max tow package 1500’s is that they get a 10” Dana super 60 and a GCWR of 18,200 while the rest of the trucks have a GCWR of 17,000 and I believe a 9.25” rear end. Thanks!