Are They Meaningless? Tow Limits, Payload and Axle Load

[richard5933]

Originally Posted by switz

Just an observation. The SUV has seating for seven folks. Corpulent Americans averaging 225 pounds each are the passengers for a total load of 1,575 before purses etc. The door label is let's say 1350 pounds. Does anyone really worry that the car is overloaded?...

You would have had a good time watching my father load the family's station wagon (Pontiac Grand Safari w/455) as we headed out for our two weeks of vacation in the Catskills each summer. There were my parents, myself, and three brothers. And all the luggage. And the dreaded bathroom scale to weigh each piece as it went into the back of the car. The process caused more than one tear to be shed as something was left behind to make it under the weight limit, especially in the early years when the baby's things took up half the allotted weight.

My guess is you're right that most people don't worry about things like this anymore. But judging by the condition of some of the cars I see on the road, and the number of them with the tail dragging and nearly touching the road, perhaps they should. Same for the number of loaded pickup trucks I see going down the road with their headlights pointing up to the sky.

[Gotta_Travel]

This thread has gone on so unnecessarily long. I guess the real question to open the thread should have been: “Do you want to be this guy?”

https://www.rgj.com/story/news/2021/...azteYRioqYPNyw

[emoji6]
Cheers,

[jcl]

Originally Posted by Gotta_Travel

This thread has gone on so unnecessarily long. I guess the real question to open the thread should have been: “Do you want to be this guy?”

https://www.rgj.com/story/news/2021/...azteYRioqYPNyw

[emoji6]
Cheers,

That guy? The commercial operator driving without a driver's license, or functioning trailer brakes? Lock him up.

Note that they didn't list any charges related to the trailer being overweight, which it apparently was. Those would be listed under the commercial operator charges that they say are still to come.

[Countryboy59]

Originally Posted by switz

Just an observation. The SUV has seating for seven folks. Corpulent Americans averaging 225 pounds each are the passengers for a total load of 1,575 before purses etc. The door label is let's say 1350 pounds. Does anyone really worry that the car is overloaded?

What about that same person load plus luggage in the back at the airport? No cabby will miss a fare with the upcharges.

There are very few of the standard weight drivers of 150 pounds in the USA per the various pickup vehicle manufacture's charts.

So the question then becomes, because the operator's large number of folks family is all obese, they have to get a school bus for the family vehicle?

Now vary the story that the operator is now picking up five of their friends to go to dinner. Would you ask each person their weight?

The ground personal use vehicle world is not like an airplane where a specific load and where it can be carried is detailed in loading charts.

I have seen sedans with seating for five with less than 850 pounds payload.

Common sense is not common anymore in the USA. Today's youth can't make change in the head, but require a digital cash register. They load their vehicles without a thought of weights or the weight placement.

Wonder how we are still alive.....

Vehicles (at least the ones I buy) are heavy duty enough to handle the load of passengers. I routinely see large SUVs towing and full of passengers without issue.

People get in trouble when they overload the smaller SUVs that have somehow had seven seats crammed into them. But the large trucks and wagons can handle it.

[RedSHED]

Originally Posted by richard5933

Third (or more) time answeing...this time I'll pare it down to the basics...

Because a vehicle is more than the axles. Period.

Yep. Sprung vs unsprung weight, heat rejection, frame/body strength... the list wanders on.

[Dennis C]

Unfortunately there are too many of these people out on the roads.

[Gotta_Travel]

Originally Posted by jcl

That guy? The commercial operator driving without a driver's license, or functioning trailer brakes? Lock him up.



Note that they didn't list any charges related to the trailer being overweight, which it apparently was. Those would be listed under the commercial operator charges that they say are still to come.

One word: analogy [emoji6]

[JPinTO]

I have a 2010 Flying Cloud 23’ which has been towed by a 2008 E70 X5 4.8L. The X5 had a reinforced WD hitch, massive brakes, rear air springs, decent V8 torque. Matched with the narrow 23’ dual axle AS and mainly flat southern ontario countryside, the X5 met our towing requirements “safely” for a decade.

The X5 is recently gone, and I am researching a new TV. This (very long) thread has provided me with a few practical learnings regardless of the next TV that we select.

- Airstream Tire pressures around 55-60 PSI. I ran at 50, so I will bump PSI up a little
- Tow vehicle rear tire pressure: Add 5 PSI when towing (only to rear)
- Tongue weight: keep at 10% of trailer weight. I will be buying a scale and using it to better position cargo in the trailer
- Keep weight off the Trailer tail: Going to move tools and heavier items out of the rear AS trunk and rear shower.

[GettinAway]

Originally Posted by JPinTO

I have a 2010 Flying Cloud 23’ which has been towed by a 2008 E70 X5 4.8L. The X5 had a reinforced WD hitch, massive brakes, rear air springs, decent V8 torque. Matched with the narrow 23’ dual axle AS and mainly flat southern ontario countryside, the X5 met our towing requirements “safely” for a decade.

The X5 is recently gone, and I am researching a new TV. This (very long) thread has provided me with a few practical learnings regardless of the next TV that we select.

- Airstream Tire pressures around 55-60 PSI. I ran at 50, so I will bump PSI up a little
- Tow vehicle rear tire pressure: Add 5 PSI when towing (only to rear)
- Tongue weight: keep at 10% of trailer weight. I will be buying a scale and using it to better position cargo in the trailer
- Keep weight off the Trailer tail: Going to move tools and heavier items out of the rear AS trunk and rear shower.

We had a 23FB for many years. The FB does have a very light tongue weight. I think it has more of a tendency to sway vs the 25FB, which has twice the tongue weight. We found the 23FB was more stable in relation to sway when we ran with the fresh water tank full. There are two 23’ AS threads here on the forum. One for CB (corner beds) and one for FB. Lots of great info on both threads.

[switz]

The specs for the 2023 Toyota Sequoia (completely new drive train with 10 speed tranny and a hybrid option with more power and torque than the 5.7L V8) include towing capability of 9,000 pounds. However the payload is around 1,600 pounds before "stuff".

Our 2007 Mercedes ML320 CDI turbo diesel died at 207,000 miles and it towed our 6,000 pound 2015 23D International Serenity very well at 55 mph which was the sweet spot for that drive train.

The replacement is our 2021 Toyota Land Cruiser. (one of the last new ones for the USA as the 300 series will not ever come here) It is rated for a 8,100 pound trailer but the payload numbers make that an impossibility with 15% tongue weight. Our 23D has about a 900 pound tongue weight and that works fine for our numbers.

[DewTheDew]

Originally Posted by switz

The specs for the 2023 Toyota Sequoia (completely new drive train with 10 speed tranny and a hybrid option with more power and torque than the 5.7L V8) include towing capability of 9,000 pounds. However the payload is around 1,600 pounds before "stuff".

Our 2007 Mercedes ML320 CDI turbo diesel died at 207,000 miles and it towed our 6,000 pound 2015 23D International Serenity very well at 55 mph which was the sweet spot for that drive train.

The replacement is our 2021 Toyota Land Cruiser. (one of the last new ones for the USA as the 300 series will not ever come here) It is rated for a 8,100 pound trailer but the payload numbers make that an impossibility with 15% tongue weight. Our 23D has about a 900 pound tongue weight and that works fine for our numbers.

Just to note that while the Land Cruiser will not come here, the Lexus LX (gussied up Land Cruiser) will.

[director14]

Originally Posted by JPinTO

I have a 2010 Flying Cloud 23’ which has been towed by a 2008 E70 X5 4.8L. The X5 had a reinforced WD hitch, massive brakes, rear air springs, decent V8 torque. Matched with the narrow 23’ dual axle AS and mainly flat southern ontario countryside, the X5 met our towing requirements “safely” for a decade.

The X5 is recently gone, and I am researching a new TV. This (very long) thread has provided me with a few practical learnings regardless of the next TV that we select.

- Airstream Tire pressures around 55-60 PSI. I ran at 50, so I will bump PSI up a little
- Tow vehicle rear tire pressure: Add 5 PSI when towing (only to rear)
- Tongue weight: keep at 10% of trailer weight. I will be buying a scale and using it to better position cargo in the trailer
- Keep weight off the Trailer tail: Going to move tools and heavier items out of the rear AS trunk and rear shower.

I travel the roads of southern ontario just like you. My setup was done by CanAm RV in London. They will be able to answer any questions you have. The same family have been fabricating custom hitches/receivers since 1970 as well as being an award-winning Airstream dealership. Give them a chance. It never hurts to listen.
Cheers, Paul

[BayouBiker]

Originally Posted by jcl

Well, that doesn't answer the question, but thanks for trying.

Have a good day

Actually it does.... In other words, both a loaded vehicle or a towing combination is more complicated than a simple component or single system.

Thus one should not assume as a general rule that a vehicle loaded with a trailer on a ball along with a WD hitch will perform exactly the same, or as stably, or with the same dynamic load and wear characteristics as the same vehicle loaded in such a way that the static loads are the same.

[Bobbo]

Originally Posted by BayouBiker

Actually it does.... In other words, both a loaded vehicle or a towing combination is more complicated than a simple component or single system.

Thus one should not assume as a general rule that a vehicle loaded with a trailer on a ball along with a WD hitch will perform exactly the same, or as stably, or with the same dynamic load and wear characteristics as the same vehicle loaded in such a way that the static loads are the same.

Wow. Eight months later.

[BayouBiker]

Nothing like resurrecting memories from the stale past, even if they deserve to be buried. You're welcome...

[gypsydad]

Originally Posted by BayouBiker

Nothing like resurrecting memories from the stale past, even if they deserve to be buried. You're welcome...

Agree; but we haven't had a good argument here for some time!

[DCPAS]

Originally Posted by gypsydad

Agree; but we haven't had a good argument here for some time!

https://www.youtube.com/watch?v=ohDB5gbtaEQ

[BayouBiker]

Having paid for another 60 minute session, I must say I remain astonished there remain folks here arguing they can safely exceed manufactures guidance for tongue weight. Most particularly those with affinity to European performance SUV's. They seeminly contradict manufacturers guidance and suggest or state outright there is no risk of oversteer and sway but instead claim the engineers foolishly specified weak hitches and failed to take advantage of the wonders of WD to overcome axle load limitations.

Although this actual issue has ben described previously, I'll do so again here:

Stability in physics refers to situations where if a system is perturbed from equilibrium, the torques arise that self drive the system back to equilibrium. Consider a long cylinder standing on end on a table. It is in equilibrium. Further, if you tip it just a bit, the resultant torques drive it back to its resting state and it returns to static equilibrium standing upright. However if it is tipped too far or subjected to too much lateral force, the cylinder will become unstable and fall over. It has a tipping point.

In towing, this situation arises in a similar fashion. For example, if trailer ball yaw angle is excessive or yaw forces are too great, reactive forces acting on the tow vehicle's rear tires cause them to deform excessively or in severe situations loose traction entirely and thus fail to track inside the radius of the corresponding front tires as they should for neutral steering response. At this point the combination is beyond a tipping point and will not self correct, instead the driver or some other stimulus must rapidly correct to avoid reaching a critical point where complete loss of control will occur. Another situation like this involves trailer sway that will amplify until oversteer takes over and the combination also spins out of control.

Tongue weight is an excellent but not complete proxy for the magnitude of torques involved in determining tow combination stability with respect to oversteer and sway. Manufacturers use tongue weight guidance as a tool to limit stability issues.

Simple and relatively safe tests can be performed to check for stability issues as they cannot be detected or predicted from handling demonstrations yet you never see anyone citing results to support their contention these tow combinations are safe. Why is that?

[Profxd]

Look who’s come out of hibernation!

[switz]

Not really discussed in all the statistics about load, tongue weight etc is the effect of speed.

I have driven on a race track at speeds way above the highest posted speed limits (which are often ignored even by folks towing).Events seem to occur geometrically faster as the speed goes up.

It is a reality that as we age, our reactions and perceptions of situations slow down.

The best setup rig driven by a senior citizen at higher speeds that suddenly develops a serious handling issue for any reason may not have a good outcome.

I suggest slowing down and seeing the scenery and arriving relaxed can help compensate for the rig's imperfections. The bonus is less fuel used as well.

A rule of thumb that seems to work is that each 10 mph increment above 55 decreases fuel economy by another 10%.