What determines Capacity

[ocbinva]

I have a 2017 quad cab 4x4, 5.7 with 3:21 gears. Looking at the towing guide the max towing capacity is 8000. However the same truck with same transmission but with 3:92 gears has a max towing of 10150. How does gearing make it jump that much? My assume towing capacity was based on suspension and increased frame size. I am debating on installing 3:92 just for that extra capacity. Thoughts?

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[crash68]

manufacturers use the SAE J2807 standard to determine towing/hauling capacity. It's a bunch of tests on how fast a vehicle can repeatedly get a load moving up a hill, up to a certain speed, etc. without overheating or errors.
Lower gearing will get loads moving quicker due to the torque multiplication

 

[mtofell]

When talking towing and weights remember two important but very different concepts - what can the truck carry? What can the truck pull?

Carry is things like suspension, frame, brakes. Pull is things like engine, tranny, gears. Yes, there is a bit of cross-over as the truck needs bigger brakes to help stop a bigger trailer but generally the trailer should stop the trailer and the truck should stop the truck (keep in mind the "truck" is carrying tongue or pin weight of the trailer thus truck brakes are stopping that part of the trailer).

It gets confusing and these net message boards are loaded with good and bad info. Just keep researching and learning.

 

[BossHogg]

I have a 2017 quad cab 4x4, 5.7 with 3:21 gears. Looking at the towing guide the max towing capacity is 8000. However the same truck with same transmission but with 3:92 gears has a max towing of 10150. How does gearing make it jump that much? My assume towing capacity was based on suspension and increased frame size. I am debating on installing 3:92 just for that extra capacity. Thoughts?

There was a time not long ago when, for example, Ford would remove bumpers to falsely increase payloads. Thankfully these days are long gone since the acceptance of the J2807 standard. That is good news for us.

You may find this interesting, TFL spend sometime with RAM engineers on the test tracks going over some of the J2807 specifications and how they test.

After watching the video, it is much easier to understand why adding, for example, airbags, can't change the vehicle's payload and tow-weight numbers.

 

[ocbinva]

Wow Great info. I have done tons of reasearch. I made sure my trailer is is within allowances and have a 20% cushion. I have also determined with hitch weight and passengers what my truck capacity is. It will take some prudent planning when hauling motorcycle but it is still within standards.

I was trying to determine if getting 3:92 gears would be worth it since that is the only difference in the Ram chart that takes me from 8000 to 10150. Just never heard how gears impact capacity Every one's explanation helps quite a bit.

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[13ram1500crew]

Wow Great info. I have done tons of reasearch. I made sure my trailer is is within allowances and have a 20% cushion. I have also determined with hitch weight and passengers what my truck capacity is. It will take some prudent planning when hauling motorcycle but it is still within standards.

I was trying to determine if getting 3:92 gears would be worth it since that is the only difference in the Ram chart that takes me from 8000 to 10150. Just never heard how gears impact capacity Every one's explanation helps quite a bit.

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Gears will help you pull the weight, but it wont "officially" change the tow rating... But if your going to be using it, go ahead and do it.

 

[dhay13]

Changing gears won't 'legally' change your tow capacity but will improve the 'feel' of it. No matter what you do to your truck the factory max tow capacity will still be 'about' the 8000lbs you noted.

 

[68PowerWagon]

If you will be towing a fairly often & can afford it, I highly suggest bumping up to the 3.92's. I bumped my 2500 from 3.73's to 4.56's. I have not towed my heavy 5th wheel yet, but I did pull about 4,500 pounds the other day on my utility trailer & noticed a big difference. It is not constantly having to down shift which will make it easier on my tranny. I believe you have the 8 speed tranny so that already helps you out a bit but the gear change will really help yank it down the road.

 

[csuder99]

Changing gears won't 'legally' change your tow capacity but will improve the 'feel' of it. No matter what you do to your truck the factory max tow capacity will still be 'about' the 8000lbs you noted.

Here we go again .... The challenge is still on, show us a federally mandated sticker on your truck or a legal document like a registration that states the maximum tow rating. Web sites or owners manuals don't count as they are not legal documents. SAE J2807 is a engineering document and manufacturers agreed to test in accordance with it but it's purpose is to make it a somewhat apples to apples comparison, not a legal requirement.

 

[dhay13]

Here we go again .... The challenge is still on, show us a federally mandated sticker on your truck or a legal document like a registration that states the maximum tow rating. Web sites or owners manuals don't count as they are not legal documents. SAE J2807 is a engineering document and manufacturers agreed to test in accordance with it but it's purpose is to make it a somewhat apples to apples comparison, not a legal requirement.

Perception is reality. You go to court and the attorney says 'maximum factory rated tow capacity' and those 12 'peers' are going to tend to believe the manufacturer over some random forum guy saying it means nothing.

 

[csuder99]

Perception is reality. You go to court and the attorney says 'maximum factory rated tow capacity' and those 12 'peers' are going to tend to believe the manufacturer over some random forum guy saying it means nothing.

The random forum guy (and yes IANAL) bets $100 that the attorney is going to make the case for unsafe and negligent towing based on axle ratings and payload because these are stated on the federal vehicle certification sticker. Or possibly for a trailer being loaded incorrectly even if the trailer weight is below the rated maximum.

By your logic if somebody doesn't like the RPMs of the 3.92 gearing and changes it to 3.21 he could still tow the same trailer weight as if he had 3.92. Right ?

 

[BruceMorgan]

Here we go again .... The challenge is still on, show us a federally mandated sticker on your truck or a legal document like a registration that states the maximum tow rating. Web sites or owners manuals don't count as they are not legal documents. SAE J2807 is a engineering document and manufacturers agreed to test in accordance with it but it's purpose is to make it a somewhat apples to apples comparison, not a legal requirement.

What’s a “legal document”?

Imagine an overloaded truck was in an accident, and someone put FCA down as a plaintiff claiming liability on their part.

FCA would send a team of lawyers and engineers explaining exactly the testing methodology that led to those door stickers. And they would point out disclaimers in the owners manuals and towing guides. They do matter. If you exceed them it’s on you.

If you changed the rear end from 3.21 to 3.92, then the newly appropriate row in the towing guide would apply. I don’t know if you could get a new door sticker, and that would be a minor point of argument in court if you didn’t. But you could easily get an expert witness to say in this case a new door sticker wasn’t necessary and the higher number applied due to the 3.92.

Edit: if you dropped from 3.92 to 3.21, the other side could argue via expert witnessses you’re overloaded at the old 3.92 weight. You’d probably lose that one. Those 12 peers would hear a maximum and you exceeded it. Simple story to tell, hard to rebut.

 

[csuder99]

If you changed the rear end from 3.21 to 3.92, then the newly appropriate row in the towing guide would apply. I don’t know if you could get a new door sticker, and that would be a minor point of argument in court if you didn’t. But you could easily get an expert witness to say in this case a new door sticker wasn’t necessary and the higher number applied due to the 3.92.

Exactly my point. But whenever the topic of lowering gearing to increase towing capacity comes up people jump in insisting that you can't change the "legal tow rating". There is no need for a new door sticker because the tow rating isn't on the sticker to begin with. Which circles back to the fact that there is no "legal document" (meaning required by law such as the certification sticker or the registration) that actually states the tow rating or GCWR. Even commercial trucks only have the GVWR on the door.

Let me play devil's advocate: The defendant is asked if he knew what the maximum tow rating is and he gives some number he found somewhere in the owners manual or the Internet. Unless the owner knows and understands the details of the vehicle he would have no reason to suspect that the number doesn't actually apply to his vehicle. I can find three different numbers for my truck even knowing the gearing.

 

[BruceMorgan]

Exactly my point. But whenever the topic of lowering gearing to increase towing capacity comes up people jump in insisting that you can't change the "legal tow rating". There is no need for a new door sticker because the tow rating isn't on the sticker to begin with. Which circles back to the fact that there is no "legal document" (meaning required by law such as the certification sticker or the registration) that actually states the tow rating or GCWR. Even commercial trucks only have the GVWR on the door.

Let me play devil's advocate: The defendant is asked if he knew what the maximum tow rating is and he gives some number he found somewhere in the owners manual or the Internet. Unless the owner knows and understands the details of the vehicle he would have no reason to suspect that the number doesn't actually apply to his vehicle. I can find three different numbers for my truck even knowing the gearing.

I agree with you.

The door sticker is one thing, the tow guide is another. There are disclaimers galore about it’s your responsibility to know how your vehicle is equipped to tow safely. That seems like common sense to me.

 

[BossHogg]

I know there are a few states, like Florida, where you can be charged with a felony if you caused an injury accident while overloaded (payload). I've seen some pickups with unbelievable tow number ratings that would challenge the vehicle's payload numbers once the tongue/pin weight of the trailer was factored in.

So a truck with a stated tow number of 10,150 pounds is looking at a tongue weight between 1,000 and 1,300 pounds if the trailer is loaded properly. Add in the weight of the driver and other gear and the vehicle's payload is likely overwhelmed.

I look at the payload and tow numbers as a reference for making common-sense choices.

 

[dhay13]

My daughter bought a brand new 2016 Wrangler Unlimited Sahara and had a 4" lift, 35's and 4.88's installed. When she bought it I tried to talk her into getting the 3.73's because it was rated to tow either 3000 or 3500 (can't remember now). But with the 3.21's it was only rated to tow either 1500 or 2000. Her argument was she didn't want to pay the extra for the 3.73's when she was swapping them anyway. In the end she got the 3.21's and had all the upgrades done. No matter, her Jeep is only 'legal' to tow the factory 1500 or 2000 (whichever it was) even thought it has 4.88's now. As per her argument she should 'legally' be able to tow 5000lbs now because she exceeded the 3.73's?

 

[dhay13]

BTW-I think this is a good discussion. Not necessarily being argumentative. I don't know that I have ever seen an 'official' tow rating other than what the manufacturer states. But in my opinion a jury will go off of what the dealer advertises and to fight that will cost you thousands in expert witness fees.

And my thoughts on going from 34.92 to 3.21 you would still be rated to tow what the manufacturer states. If you do a search on the VIN number (or call a dealer and have them look it up) it will still state the higher weight. No different then pulling your hemi and dropping in a 150HP 4 banger. The legal tow rating will still be the manufacturers rating. That's my thoughts.

 

[mtofell]

If one were to be charged with negligence due to being overweight, your attorney would certainly argue that with the upgraded gears your truck is comparable to one rated higher if, in fact, the gearing was the only difference. Your defense team would hire an expert witness engineer that would testify that your truck is comparable. Sure, it could be a headache but juries are logical and I think there is a better chance than not that the physical characteristics and reality would overrule a door sticker.

All the talk about "legality" is kind of meaningless since once you're in court it will be expert witnesses and engineers arguing for both sides. If my expert witness engineer can show a physically comparable truck to one with ratings I was within there is a good chance you will prevail. Of course, court is expensive and a HUGE hassle and no one wants to be there.

These arguments are kind of pointless, though. It reminds me of a bunch of kids on the playground arguing which superhero would win in a battle. Nobody knows what WILL happen.

 

[BruceMorgan]

BTW-I think this is a good discussion. Not necessarily being argumentative. I don't know that I have ever seen an 'official' tow rating other than what the manufacturer states. But in my opinion a jury will go off of what the dealer advertises and to fight that will cost you thousands in expert witness fees.

And my thoughts on going from 34.92 to 3.21 you would still be rated to tow what the manufacturer states. If you do a search on the VIN number (or call a dealer and have them look it up) it will still state the higher weight. No different then pulling your hemi and dropping in a 150HP 4 banger. The legal tow rating will still be the manufacturers rating. That's my thoughts.

You’re forgetting that FCA will say those numbers are for how they built the truck, not how you modified it. “OEM rating” (I’ll stop using the word legal) will go out the window, and now yes you’re paying expert witnesses to debate whether what your doing was stupid or reasonable.

Edit: you have to realize that operator error vs manufacturer error is argued daily in courtrooms across the country. I sat on a medical malpractice jury for three weeks debating who screwed up. Operator error was our verdict (the surgeon). Lots of expert witnesses, and the artificial hip manufacturer, etc.

This is why blow dryers say to not use them in the bathtub.

 

[Jerrybob]

My new RAM 1500 with a 3.92 and tow package is max tow rated at 11,620lbs with a 1770 lbs max payload.