Community Forums

blw2k1 · 04-07-2021, 08:31 AM

My tow vehicle owners manual states that the maximum tongue weight rating is 350lbs. That is exacatly 10% of the max tow capacity (3500lbs). I've looked at the owners manuals of several different vehicles and they almost always state the max tongue weight is 10% of whatever the towing capacity is (although toyota vehicles usually state 9-11%).

My question is: how is this max tongue weight determined? Is it a max rating of the hitch itself? Is it the limits of the vehicle suspension or frame? Is it just that 10% is the safe tongue weight for towing?

The reason I ask is that I have a PUP with a very high tongue weight. GTW of about 3100lbs and tongue weight over 500lbs. I'm looking for a new vehicle and I'd like to stay with a mini van or small SUV, but most of these vehicles are 3500lbs towing, and 350lbs tongue weight.

propchef · 04-07-2021, 08:48 AM

Search is your friend. This topic is covered in-depth in numerous places on this forum.

Be prepared to get many differing opinions.

530ktm · 04-07-2021, 08:49 AM

If your tongue weight is 350lbs then your tongue of 500lbs is too heavy. The tongue weight is not the maximum tow weight which is what the vehicle weighs. 500lbs for the tongue is a heavy beast. So yes, that 350lb weight is what is recommended for the hitch and the vehicle it is attached to.

blw2k1 · 04-07-2021, 08:52 AM

Quote:

Originally Posted by propchef

Search is your friend. This topic is covered in-depth in numerous places on this forum.

Be prepared to get many differing opinions.

I have done a lot of searching. And I have found no answer. Most of the tongue weight discussion I've seen are around WDHs. I want to leave that part out for now ;-)

groswald · 04-07-2021, 09:21 AM

Maximum tongue weight is a hitch specification as is overall hitch capacity. Both should be stated somewhere on the hitch, either as a placard or stamped into the steel. Vehicle manufacturers may provide specific values for their chassis as well. If they do, the lowest value always applies.

As for how the numbers are arrived at... You're not likely to get a good answer unless someone who designs them weighs in.

That said, it's a function of

physics - what forces are at play and in what directions
mechanical engineering - how do we design a hitch to adequately counter those forces with an appropriate margin of error
materials science - what materials in what configurations will fit the desired strength/weight/cost parameters in implementing the design
legal - what do we have to do to keep ourselves out of court

Or, overbuild it and attach spec's to it that have been proven reasonable over time.

Regardless of how the figure was arrived at though, exceeding the manufacturer's specification makes you liable for any and all consequences that may arise from exceeding them.

There are many here who will say, "Go for it. They'll never be able to prove you overloaded it if it fails." Not true, I'm afraid. Failure mode analysis can tell the difference between failures caused by manufacturing issues, defective materials, fatigue (long term wear), and catastrophic failure (overloading).

At the end of the day the real question is, are you willing to take the risk?

Regards,

Randy

keymastr · 04-07-2021, 12:22 PM

The smaller tow vehicles you are referencing have no actual frame, they are unibody vehicles that use the sheet metal body of the car as the support structure and therefore are limited as to what weight they can carry safely.

These vehicles also are limited by the weight they can pull without overworking the engine and most importantly the transmission. Most smaller SUVs and mini vans have transmissions that are not made for heavy towing and especially if you have it full of passengers and gear. Pay very close attention to the payload which includes all people and gear in the vehicle as well as the tongue weight of the trailer. Often just passengers and gear will leave you with almost no allowable weight for the trailer with these smaller vehicles.

shane_the_ee · 04-07-2021, 12:44 PM

Quote:

Originally Posted by blw2k1

My question is: how is this max tongue weight determined? Is it a max rating of the hitch itself? Is it the limits of the vehicle suspension or frame? Is it just that 10% is the safe tongue weight for towing?

There’s no hard and fast rule for determining max tongue weight*. And each manufacturer gets to pick their own margins for each component and/or subsystem. And they also have to think about how the vehicle is going to be used: how often will it be used to tow, for how long, at what speeds, etc, etc. It could be that the frame isn’t strong enough, it could be that the transmission will burn up if you were to try and tow a 3500lb trailer across the Arizona desert at 85mph and 130deg F, it could be that the suspension bushings will wear out before the warrantee is up. It can even be because the manufacturer has a bigger truck they’d rather sell you if you’re doing a lot of heavy towing...

*Note, there is a maximum receiver weight for just the hitch which is just looking at the structural strength of the hitch receiver itself.

Dave Pelletier · 04-07-2021, 01:11 PM

what they said. Also keep in mind that to be safe you should have a tongue weight of 12 - 15% which for a 3500lb trailer is 420 - 525lbs....10% may well be to light and sway issues may ensue. I'd recommend sticking with a tow vehicle with at least a 5000/500 lb capacity

Dave

Kid Gloves · 04-07-2021, 01:24 PM

Try shifting the stuff in the PUP, heavy stuff to the rear, light stuff to the front, so that you end up with a 3100lb trailer and tongue weight of 350lbs.

nicky8668 · 04-07-2021, 01:38 PM

If I have to choose between overload the tongue or trailer weight, I’ll choose to overload the trailer weight. Overload what the hitch can handle can compromise the hitch physical integrity. You don’t want to your hitch fall apart while towing.

Desert Flyer · 04-07-2021, 10:56 PM

For a popup, you don’t need to go up to 15% tongue weight...10% should be fine due to lower height subject to wind. The 350-lb limit happens to be the demarcation between a class 2 (solid 1-1/4” towbar) and class 3 (2”hollow tube towbar) hitch rating. So, for a manufacturer of a light duty CUV/car/minivan the 350 lb limit is a natural one. No reason to go higher unless to a more medium duty SUV in the 500/5,000 lb towing zone and higher.

move on · 04-08-2021, 02:14 AM

On an SUV with unibody construction the tongue weight might be limited by the way the hitch is mounted and how the hitch loads are spread out over the body. It might also be limited by how much the tongue weight affects the payload and rear axle load. As for how the tongue weight affects the handling of the rig it is typically accepted that it should be within the range of 10% to 15% of trailer weight. At less than 10% the trailer could sway and at more than 15% the tow vehicle could oversteer and a jackknife could occur. There are exceptions. Some SUVs allow 8% or even less tongue weight. There are lots of factors that go into the answer that only the vehicle manufacturer can tell you, which is why you have to go by his owners manual.