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Frustrated Calculating Towing Capacity

 
Old 05-31-2019, 02:44 PM
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Default Frustrated Calculating Towing Capacity

OK, newbie. Just bought a 2019 Lariat. It is 4x4, 20" tires, 157" wheelbase, 3.5l, 355 axle ratio, max towing package. The Ford towing guide says I can tow up to 12,900 (I know that's a little sales talk). My frustration with this and other sites is that there doesn't appear to be a clear cut formula for calculating the true towing capacity. The GVWR is 7050. The combined weight of occupants and cargo never to exceed 1680. The GCWR is 18,400.

Can someone please clarify for me. Thanks
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Old 05-31-2019, 03:46 PM
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The truck will pull 12,900 lbs, but your suspension isn't designed to hold more than 7050 lbs. It is the suspension that will limit how much you can tow. The max combined weight of the truck and trailer shouldn't be more than 18,400 lbs. The total weight of the truck and everything in it including passengers and tongue weight from a trailer shouldn't be more than 7050. If you subtract the 1680 from 7050 that means your truck actually weighed 5370 when it rolled off the assembly line. If you've not done any modifications to the truck, and you don't normally carry a lot of tools or other gear the 1680 is pretty accurate. If you have then it is best to actually weigh the truck. Mine has a posted payload of 1621, but I have a 200 lb cap on mine reducing real payload to just over 1400 lbs.

You need to calculate about 13% of a trailers weight to get an estimate of tongue weight. If you are pulling a 7000 lb trailer that would add about 910 lbs on the tongue. You'll need to add a weight distribution hitch to tow that much and that is another 100 lbs. So figure 1000 lbs on the hitch for the trailer. That leaves 680 lbs for passengers and other gear in the truck which is reasonable.

In the real world 6000-8000 lbs is pretty close to max with most F150's. But the payload number varies by truck, 1600-1800 is pretty typical so you're right there. But some trucks have as little as 1100 lbs, others are over 2000. It just depends on the truck. A 4X4 Supercrew loaded up with options like a Platinum may only have 1100 lbs payload. An XL, 4X2 with the regular or supercab might be over 2000. They make a heavy duty payload version that will add 800 lbs to the payload and GVWR.

If you need more than 680 lbs for everything in the truck then 7000 lbs is too much trailer. If you can get by with only about 400 lbs in the truck then you can tow a heavier trailer. When packing every 100 lbs you can get out of the truck and into the trailer only adds 13 lbs to the tongue weight while taking 100 lbs out of the truck. Packing carefully can mean pulling a little heavier trailer.

Last edited by marshallr; 05-31-2019 at 03:48 PM.
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Old 05-31-2019, 03:53 PM
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11,200 max at 15% tw and a 100% empty truck based off your 1680 payload. Any thing or body you put in it will drop that number though. If you are towing a boat or some utility trailers that run a lower percentage tw then you might see your 12,900 max.

you need to figure out what your loaded truck will way, figure out the remaining payload then divide it by .15.
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Old 05-31-2019, 05:25 PM
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Originally Posted by smolenr View Post
My frustration with this and other sites is that there doesn't appear to be a clear cut formula for calculating the true towing capacity. The GVWR is 7050.
It's really quite simple once you know the basics..

Ignore all the other numbers an concentrate on GVWR of the tow vehicle. For most of us payload capacity available for hitch weight is the limiter as to how heavy a trailer you can tow without being overloaded. Payload capacity available for hitch weight is GVWR of the truck minus the wet and loaded weight of the truck when ready to tow.

The frustration is because you won't find that number anywhere. The number you need requires the weight of the wet and loaded tow vehicle, and nobody knows the weight of people and gear you will haul in your truck when towing. The gross payload capacity of your truck is on the yellow sticker in the driver's door jamb, but most of us are awful when it comes to guesstimating weights of people, aftermarket options, pets, tools, toys and other items that will be in the truck when towing. I don't try to use that number to guesstimate the payload capacity available for hitch weight. To have an accurate weight, you must load the truck with everybody and everything that will be in it when towing, fill up with gas, then weigh the wet and loaded truck. Subtract the weight of the wet and loaded truck from the GVWR of the truck and the answer is the payload capacity available for hitch weight.

Now, if you did a good job of loading everybody and everything in the truck before weighing it, you have the basic info you need to use junior-high math to calculate the max trailer weight of any normal TT you can tow without being overloaded.

Subtract 100 pounds from the payload capacity available for hitch weight to get payload capacity available for tongue weight (TW). (That 100 pounds is for the weight of a quality weight-distributing (WD) hitch with good built-in sway control, such as an Equal-I-Zer 4P or Blue Ox SwayPro).

Divide the payload capacity available for TW by 15% to get a conservative max trailer weight. Divide the payload capacity available for TW by 13% to get the max trailer weight of a properly-loaded trailer that has average TW.

Last edited by smokeywren; 05-31-2019 at 05:38 PM.
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Old 05-31-2019, 07:09 PM
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Originally Posted by marshallr View Post
The truck will pull 12,900 lbs, but your suspension isn't designed to hold more than 7050 lbs. It is the suspension that will limit how much you can tow. The max combined weight of the truck and trailer shouldn't be more than 18,400 lbs. The total weight of the truck and everything in it including passengers and tongue weight from a trailer shouldn't be more than 7050. If you subtract the 1680 from 7050 that means your truck actually weighed 5370 when it rolled off the assembly line. If you've not done any modifications to the truck, and you don't normally carry a lot of tools or other gear the 1680 is pretty accurate. If you have then it is best to actually weigh the truck. Mine has a posted payload of 1621, but I have a 200 lb cap on mine reducing real payload to just over 1400 lbs.

You need to calculate about 13% of a trailers weight to get an estimate of tongue weight. If you are pulling a 7000 lb trailer that would add about 910 lbs on the tongue. You'll need to add a weight distribution hitch to tow that much and that is another 100 lbs. So figure 1000 lbs on the hitch for the trailer. That leaves 680 lbs for passengers and other gear in the truck which is reasonable.

In the real world 6000-8000 lbs is pretty close to max with most F150's. But the payload number varies by truck, 1600-1800 is pretty typical so you're right there. But some trucks have as little as 1100 lbs, others are over 2000. It just depends on the truck. A 4X4 Supercrew loaded up with options like a Platinum may only have 1100 lbs payload. An XL, 4X2 with the regular or supercab might be over 2000. They make a heavy duty payload version that will add 800 lbs to the payload and GVWR.

If you need more than 680 lbs for everything in the truck then 7000 lbs is too much trailer. If you can get by with only about 400 lbs in the truck then you can tow a heavier trailer. When packing every 100 lbs you can get out of the truck and into the trailer only adds 13 lbs to the tongue weight while taking 100 lbs out of the truck. Packing carefully can mean pulling a little heavier trailer.
OK, if I understand what you're saying, I can only really tow 7050 (GVWR), assuming that I have not modified the truck and I am the only person in it. That is towing "safely" because of the suspension system. Then there is the payload figure I need to keep in mind, which accounts for the people, dogs, hitch, WDH, kayaks, and anything else that is on or in the truck. But THAT figure cannot go over 1680. Am I getting it, yet
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Old 05-31-2019, 08:12 PM
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Originally Posted by smolenr View Post
OK, if I understand what you're saying, I can only really tow 7050 (GVWR), assuming that I have not modified the truck and I am the only person in it. That is towing "safely" because of the suspension system. Then there is the payload figure I need to keep in mind, which accounts for the people, dogs, hitch, WDH, kayaks, and anything else that is on or in the truck. But THAT figure cannot go over 1680. Am I getting it, yet
Close, the truck and everything in it including you and tongue weight cant be over 7050. The payload number is a calculation based on the weight of the truck. In your case 7050 - the weight of the truck = 1680. You can tow over 7050lbs the truck just cant weigh more than that when you do it.
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Old 05-31-2019, 08:58 PM
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Originally Posted by Jeff1024 View Post
Close, the truck and everything in it including you and tongue weight cant be over 7050. The payload number is a calculation based on the weight of the truck. In your case 7050 - the weight of the truck = 1680. You can tow over 7050lbs the truck just cant weigh more than that when you do it.
Nope, sorry, confused. Thought I had it. I'm just trying to understand, as a new truck, with the mechanics mentioned, and no other item, other than me, in the truck, what is the towing max? I'm struggling to understand why that isn't an easy number to identify. I already understand now that 12,900 ain't going to be it because of the suspension system.
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Old 05-31-2019, 09:13 PM
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OK, let me try it from this angle (PS, I appreciate everyone's patience, I just want to get it right). If my GVWR is 7050 and my payload capacity is 1680, then I'm assuming the dry weight of the truck is 5370 (7050-1680). And I need to make sure that I don't exceed the 1680, which would include hitch and WDH weight, passengers, toys in the trunk, anything else that goes in or on the truck. So if I keep it at no more than 7050, what would be the max I can tow?
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Old 05-31-2019, 09:21 PM
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Originally Posted by smolenr View Post
OK, let me try it from this angle (PS, I appreciate everyone's patience, I just want to get it right). If my GVWR is 7050 and my payload capacity is 1680, then I'm assuming the dry weight of the truck is 5370 (7050-1680). And I need to make sure that I don't exceed the 1680, which would include hitch and WDH weight, passengers, toys in the trunk, anything else that goes in or on the truck. So if I keep it at no more than 7050, what would be the max I can tow?
Bingo. It gets a bit confusing because there are several ratings, and you have to make sure you don't exceed any of them. The rating of what you can tow is different from what you can haul. Modern 1/2 Ton trucks are powerful enough that they can pull some big numbers, but their suspension systems are such that you will generally bump up against GVWR (7050lb) before you exceed what the truck can actually pull. To keep it simple make sure you are not over the 1680 and you should be good.Working backward from 1680 and making some assumptions we can figure out what kind of trailer you can pull:

1680 - 100lbs for a WDH - 180lbs for a driver leaves 1400lbs for everything else.

Your hitch is most likely rated to 1,100, another limit you cant exceed, so lets use that as the max tongue weight you can have. Assume 13% on the ball to keep the trailer stable and you are at 1,100/.13 = 8450lb max trailer weight.

This is totally a rough guess but gives you an idea of how to work the calculation.
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Old 05-31-2019, 09:33 PM
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Originally Posted by Jeff1024 View Post
Bingo. It gets a bit confusing because there are several ratings, and you have to make sure you don't exceed any of them. The rating of what you can tow is different from what you can haul. Modern 1/2 Ton trucks are powerful enough that they can pull some big numbers, but their suspension systems are such that you will generally bump up against GVWR (7050lb) before you exceed what the truck can actually pull. To keep it simple make sure you are not over the 1680 and you should be good.Working backward from 1680 and making some assumptions we can figure out what kind of trailer you can pull:

1680 - 100lbs for a WDH - 180lbs for a driver leaves 1400lbs for everything else.

Your hitch is most likely rated to 1,100, another limit you cant exceed, so lets use that as the max tongue weight you can have. Assume 13% on the ball to keep the trailer stable and you are at 1,100/.13 = 8450lb max trailer weight.

This is totally a rough guess but gives you an idea of how to work the calculation.
Thanks, I'm getting it. But I want to finish with the stuff I have. I'm using an Equalizer hitch, but the figures on the manual say 400 lb max loaded tongue and 4000 lb max loaded trailer weight. Which figure would I use for 1,100 in your example above?
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