Weight distribution - Axles - Tires

[Tireman9]

I note in Airstream Classic Owner's Manual the instruction to place all trailer tires on a platform scale and that that total "cannot" exceed the total GAWR. I do have to wonder how the factory managed to design the TT so the weight on 4 tires was evenly distributed between the axles and the tires.


Has anyone ever confirmed that their weight is perfectly distributed between the axles and evenly split 50/50 side to side?



How did you interpret the word "Cannot"? Does this mean there is something in a Classic that will prevent overloading? I would not think so.


IMO "Should not" would be better wording as that would be considered an instruction to the owner.

[TouringDan]

Tireman9

I agree the wording should be “should not” but also the word “twice” should be added since there are 2 axles.

I am not sure about the distribution. I probably wouldn’t worry about it.

Dan

[SeaLevel]

Originally Posted by Tireman9

How did you interpret the word "Cannot"? Does this mean there is something in a Classic that will prevent overloading? I would not think so.


IMO "Should not" would be better wording as that would be considered an instruction to the owner.

IMO "must not" would be better than either cannot or should not. Either way, I think people get the point that it's not advisable to exceed the documented load limits.

[OTRA15]

Originally Posted by Tireman9

I note in Airstream Classic Owner's Manual . . .
. . .

It would help if everyone were reading from the same page IMO.

Here is the 2019 Classic Owner's Manual:

https://www.airstream.com/wp-content...manual-126.pdf

At the top left of p. 7-4 [PDF p. 64/100] is an illustration showing the three weights to be observed, with "2" being the operation covered here:

"2. Trailer’s weight on axles cannot exceed GAWR."

Please take the time to open the PDF and see the illustration, so that quibbling over words can be minimized. The illustration clearly shows what weights are needed IMO.

"A picture is worth a thousand words."

Questions remain, but at least everyone should see that illustration, and interpret the weight instructions within the context of the illustration.

Happy trails!

Peter

[ROBERT CROSS]

I would love to see 4 tickets...Loaded, incorrect and 'correct'. Anyone?

If say...you were 100 high on the fridge side, how would you correct? Move the fridge?

I load carefully and don't worry about it.

The weight on our axles hitched, level with WD set is 7640lb on two 3500lb axles. GVWR 7300lb.

I unload them for Winter storage or anything over 30 days, watch pressures constantly, 15 years, 3 sets, SFSG

Bob
🇺🇸

[Tireman9]

Here are the instructions.



Clearly only single scale reading.




It would be interesting to learn the facts from anyone that has done scale weights for each tire on an Airstream. I know that most RV's do not have the weight split evenly between axles and side to side. But most RVs also have larger storage areas where lota of different "stuff" can be stored.


Can anyone provide actual scale readings?

[SailorSam205]

Originally Posted by Tireman9

Can anyone provide actual scale readings?

On a SOB trailer. Weights by RVSEF.

............1,600.... 1,450
Truck 950(tw)
............1,400.... 1,550

My fridge is relatively close to the front right wheel so that may account for the 1,600 lbs. Interesting that the left rear tire is carrying more than the right.

[tjdonahoe]

17 ram ,6.7..short boxwith 13 31’ Classic...4800...4900...7700 on trailer axles loaded

[Tireman9]

Originally Posted by SailorSam205

On a SOB trailer. Weights by RVSEF.

............1,600.... 1,450
Truck 950(tw)
............1,400.... 1,550

My fridge is relatively close to the front right wheel so that may account for the 1,600 lbs. Interesting that the left rear tire is carrying more than the right.

So if your GAWR was 3,000 You would be OK according to Airstream.


BUT you would also have two overloaded tires if the tire max was 1500.


Most cars run about 25% to 30% reserve load. Most TT older than 2017 had zero Reserve load by design.

[fwjumper]

While the most familiar definition of cannot means "not possible," there is another definition which indicates a withholding of permission. I'm guessing that AS's use of the word has more to do with liability concerns than practice in the real world. Certainly it is possible to overload, but in this context, as the manufacturer, what they are really saying is "If you do it, you're on your own." Meanwhile, we often do it anyway, intentionally or not.

cannot
modal verb us ​ /kəˈnɑt, ˈkæn·ɑt/ contraction can’t, us/kænt, kɑnt/
​
can not; to be unable or not allowed to:
I cannot imagine what will happen next.

[Offack]

Sorry, but y'all need to get out of the house and go camping!
Rick

[Wazbro]

Originally Posted by Tireman9

Most cars run about 25% to 30% reserve load. Most TT older than 2017 had zero Reserve load by design.

And yet people blame the tire failures on the tire manufacturers when the the RV manufacturers caused the problems by pushing the limits.

[Tireman9]

Originally Posted by Wazbro

And yet people blame the tire failures on the tire manufacturers when the the RV manufacturers caused the problems by pushing the limits.

Yes, this is why I brought this up. I also discovered the Airstream advice to "not exceed 106 MPH" when towing. I am sure some will use this as justification for driving at whatever speed their TV is capable of, then when there is a tire failure they will accept no responsibility for contributing to the causes for the failure.


Overloadinig+ High Speed + Low Inflation + high Interply Shear, all contribute to the cumulative damage done to the steel belt edges which is the initiation for Belt Sep "Blowout" as I have documented with an autopsy, with pictures on my posts.

[Action]

Originally Posted by Wazbro

And yet people blame the tire failures on the tire manufacturers when the the RV manufacturers caused the problems by pushing the limits.

And an RV manufacturer will do this to hit a certain price point in the market place. Since a trailer is never designed to haul people when traveling, the safety standard (or margin) could be flying under the radar. In the event of a major event there may only be property damage. AND a significant liability for the loading is on the user. The user HAS to maintain the tires at max pressure at all times, and has to replace, rotate and care to maybe a greater level. Because the tire that is riding on the edge becomes more susceptible to damage. Tow just over loaded, at higher speeds or not top off the cold pressure when needed and that tire gives up.

A tire with lots of load margin can be neglected to a small degree and still survive an event.

I didn't understand this on a 1997 brand new trailer that I got and two tires failed within 10 months of ownership. The load rating for the 4 tires combined left a 100 pound margin for the total load towed. (which was in the neighborhood of 7000 + pounds) I had no idea what individual tire loading looked liked. I was pretty ignorant at the time.

>>>>>>>>>>>>>Action

[Tireman9]

Originally Posted by Action

And an RV manufacturer will do this to hit a certain price point in the market place. Since a trailer is never designed to haul people when traveling, the safety standard (or margin) could be flying under the radar. In the event of a major event there may only be property damage. AND a significant liability for the loading is on the user. The user HAS to maintain the tires at max pressure at all times, and has to replace, rotate and care to maybe a greater level. Because the tire that is riding on the edge becomes more susceptible to damage. Tow just over loaded, at higher speeds or not top off the cold pressure when needed and that tire gives up.

A tire with lots of load margin can be neglected to a small degree and still survive an event.

I didn't understand this on a 1997 brand new trailer that I got and two tires failed within 10 months of ownership. The load rating for the 4 tires combined left a 100 pound margin for the total load towed. (which was in the neighborhood of 7000 + pounds) I had no idea what individual tire loading looked liked. I was pretty ignorant at the time.

>>>>>>>>>>>>>Action

I don't know if your TT is RVIA certified or even is any Airstream RV are. If so there is an oval sticker near the side door. RVIA establishes some minimum build standards. You can think of this like building code on a stick house. Not always the best possible but a minimum for reasonable safety.
In 2017 RVIA finally adopted a 10% reserve load for RVs as it relates to tire load capacity.
Prior to this upgrade, tires were only required to be able to support the stated GAWR when inflated to the Placard inflation. Now new RV require tire load capacity be 110% of GAWR.

Anyone get a notice or any information or suggestion to act to improve your safety from their RV company for this safety improvement? I bet not.

Action is correct about passenger exposure. Why would ST tires say for trailer use only? No passengers mean no personal injuries when there is a failure so this would obviously limit the financial exposure to only a few thousand not hundreds of thousands. IMO the "For Trailer Use Only" could be interpreted to suggest that someone might consider the tire so marked to be not as robust or maybe not as safe as tires designed for Passenger or LT vehicles.

[kb0zke]

Escapees members who are visiting Livingston can arrange for a Smart Weigh, in which portable scales are used to get the actual weight on each tire. That program also goes "on the road" at times, so it may be offered at a Rally somewhere.

[Action]

Originally Posted by Tireman9

I don't know if your TT is RVIA certified or even is any Airstream RV are.

In 2017 RVIA finally adopted a 10% reserve load for RVs as it relates to tire load capacity.

Prior to this upgrade, tires were only required to be able to support the stated GAWR when inflated to the Placard inflation. Now new RV require tire load capacity be 110% of GAWR.

Airstream RVs are RVIA certified. I seem to recall seeing that certification on my old '66 Airstream trailer. It was metal back then.

The trailer I posted about above was not a TT. And it was built new in early 1997 when I bought it in late 1997. It had new unknown brand tires out of Connecticut. (I had to call there for warranty service.) It was a boat trailer for a 27' express cruiser. The dual axle trailer was something over 30' in length. With the boat on it the length was an addition 2 or 3 feet. Scaled at 7000 to 7500 pounds. (I don't remember the specifics) The trailer weight rating was in the 9000 pound range. Everything about the trailer was up for the load except the tires. And the tires were stamped Not for passenger use, or something to that effect.

>>>>>>>>>>>>>>>Action

[Al and Missy]

Originally Posted by ROBERT CROSS

...

The weight on our axles hitched, level with WD set is 7640lb on two 3500lb axles. GVWR 7300lb.

...

Bob
🇺🇸

So with, say 850# of tongue weight your GVW is around 8490# v. a GVWR of 7300#? Maybe I shouldn't worry about being 150# over.

Al

[Jimroll]

"Should not" would sound like a suggestion, rather than an absolute limit. "Shall not" would also mean an absolute limit, as in "Shall not be infringed".