50 psi in a load range E tire??

[Phoenix]

Originally Posted by CapriRacer

Phoenix,

I can't tell from the data summary, but when was the last entry into the ST part of the poll?

The last entry on the thread was 2016. Does that mean there weren't any 2017 failures reported? If so, does that mean that ST tires are NOW doing what they were supposed to from the beginning - as in their performance is now upgraded?

==========

CapriRacer,

In recent years, the number of poll entries have decreased significantly. Not sure if there are fewer tire failures, or if new AirForums members are unaware of the tire polls and haven't shared their info. However, I suspect the latter.

Also, quite a few of the old-timers have switched to 16" wheels and LT tires, which could also affect the participation rate on the older, "mostly-ST" tire poll.

Hopefully, new 15" ST tires (like the GYE), and 15" LT tires (like the Nokian Rotiiva), are performing much better than the old GYMs. However, AirForums members who previously participated in the tire polls cannot update their recent experiences with the newer tire offerings. Therefore, it might be time to start working on a new poll; perhaps, one that consolidates ST and LT tire data.

If there are a lot of tire-related forum entries during the 2018 summer and fall travel seasons, the holidays might be a good time to release another tire poll.

Any thoughts or comments?

Phoenix

==========

"Mostly-ST" Tire Poll entries, by year:

2011 = 95 (Tire poll was created and uploaded on 05/01/2011)

2012 = 40

2013 = 54

2014 = 20

2015 = 56

2016 = 22

2017 = 5

2018 = 1 (year-to-date, as of 03/25/18)

[Action]

Originally Posted by DBinSD

For what it’s worth.

AS manual states ANY tire run at 20% or more pressure reduction from Max should be pulled of wheels and inspection done by tire professional.

20% from max tire pressure of the side wall or 20% from the AS recommended pressure from the tire inflation label?

With higher rated tires and owners changing to larger rims, most of those tires are run at 20% less than max side wall pressure. Heck the times on my TV are at less than 20% less than max side wall.

>>>>>>>>Action

[DBinSD]

As mentioned just above I miss quoted the manual.

DOT states a tire less than 70% of max sidewall pressure when HOT is under inflated.

I.E. Load range E with 80psi on wall is under inflated at 56psi hot

[Tireman9]

I do not see posts with actual side to side measured loads on each tire.
Single axle trailers should:

1. Confirm actual load on each tire
2. Calculate 115% of the heavier end
3. Check Load & inflation tables using the 115% number to learn the MINIMUM allowable inflation
4. Add 10% to that inflation number and use this new number for your goal Cold Inflation psi

Multi-axle trailers should:
1. Confirm actual loads for each tire
2. Calculate 115% of the heavier end
3. Check Load & inflation tables using the 115% number to learn the MINIMUM allowable inflation
4. Add 10% to that inflation number and use this new number for your goal Cold Inflation psi
5. If you want to lower the potential for a belt separation due to the multi-axle Interply Shear increase your CIP to the tire sidewall pressure.


This link is a Google search on Interply Shear if you want to learn more.

[GM Airstream]

Originally Posted by DBinSD

As mentioned just above I miss quoted the manual.

DOT states a tire less than 70% of max sidewall pressure when HOT is under inflated.

I.E. Load range E with 80psi on wall is under inflated at 56psi hot

Must be some of that new math... because if I take 70% of the max pressure (80 PSI) I get 56. Now you take 56 from 80 , last time I checked... gives you the baseline pressure (about 24 psi Hot) not 56 psi.

I believe that the DOT statement says less than 70% i.e you take the number and subtract it from the max... However, I didn't see any statement as to tire load vs pressure which I would think should figure into the mix too...

One of them equa'son things... so if your runn'n 24 lbs... then for sure the tire is under inflated.. and you may do sidewall damage...depending on the age of the tire...

Indeed some of you ARE getting the right stuff.... weigh'n the trailer wheel by wheel IS almost as important as proper tire pressure... they go like the horse before the cart.. but, to get the load down the road.. you need both...

[DBinSD]

Originally Posted by GM Airstream

Must be some of that new math... because if I take 70% of the max pressure (80 PSI) I get 56. Now you take 56 from 80 , last time I checked... gives you the baseline pressure (about 24 psi Hot) not 56 psi. :

Wally, Let me help you with new math.

DOT states LESS than 70% of maximum sidewall pressure HOT regardless of load is under inflated.

Therefore 69% places it in the under inflated range correct? So, 69% of 80 psi is 55psi yes?

By the way, it’s not new math last time I checked.

Regards

Dan

[switz]

When choosing after market wheels, one needs to verify that they are actually rated for the load. The 16" SenDel T03-66655T wheels Airstream installs are rated 3,580 pounds at 94 psi and the 15" SenDel To3-56545T wheels we installed on our 23D are rated 2,150 pounds at 80 psi.

Tires need to be sized to the application. Oversized tires could possibly provide a much stiffer ride if inflated to the pressures shown on the Airstream placard. Also, the factory placard really becomes useless when tires of a different size or load rating are installed.

[Tireman9]

Originally Posted by DBinSD

Wally, Let me help you with new math.

DOT states LESS than 70% of maximum sidewall pressure HOT regardless of load is under inflated.

Therefore 69% places it in the under inflated range correct? So, 69% of 80 psi is 55psi yes?

By the way, it’s not new math last time I checked.

Regards

Dan

Looking at multiple different organizations can lead to confusion unless you pay close attention.

DOT example Assume Tire sidewall pressure is 80 psi. 70% of that is 56psi. They say that no matter the load if your hot pressure is ever found to be less than 56 you have damaged the tire.

Tire industry starts with the assumption that the tire inflation has been properly set based on the actual load on a tire which should include a safety margin. RVIA current load margin is 10%. If you ever run below 80% of the inflation needed to support the measured load you have probably damaged the tire. BUT here we are talking about cold inflation pressure.


So you have two different guidelines based on two different situations.

BTW this is the first time I have heard of this DOT standard. Can someone provide a link to the source? It may be talking about passenger tires which normally have a load margin in the 15 to 25% range for cold inflation.

[DBinSD]

Originally Posted by Tireman9

BTW this is the first time I have heard of this DOT standard. Can someone provide a link to the source? It may be talking about passenger tires which normally have a load margin in the 15 to 25% range for cold inflation.

TireMan, I’ll try and grab the link tonight. I got it off the DOT US Motor Carrier site.
Dan

[DBinSD]

Originally Posted by Tireman9

Looking at multiple different organizations can lead to confusion unless you pay close attention.

So you have two different guidelines based on two different situations.

Tireman, this may be the case? I can not locate the exact link but this is the one that lead me to it. It is from CVSA about the TMC recommendation for definition of under inflation. Interested to see what your take is.

I will continue to look...

https://www.vehicleservicepros.com/v...rinflated-tire

[Action]

That article is about over the road tractor tires. The pressure range for those tires is a lot wider and the usage is much different. Hardly comparable to passenger, light truck or trailer tires.

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

[GM Airstream]

Originally Posted by DBinSD

Wally, Let me help you with new math.

DOT states LESS than 70% of maximum sidewall pressure HOT regardless of load is under inflated.

Therefore 69% places it in the under inflated range correct? So, 69% of 80 psi is 55psi yes?

By the way, it’s not new math last time I checked.

Regards

Dan

Dan...
I have looked and looked for that statement from DOT.... AS most have never heard of it before... so we called Mitch... and the tire engineer their said.. WHAT!!!!!
I explaned your posting.. and he said.. REALLY!!! don't believe that... as it used to be for farm implement and construction tires... not LT ones used on highway vehicles...
He went on to say that THEY (mitch) and other refer you to the tire load pressure requirement and not a percentage of the max rated pressure...
Matter of fact he exp on the hazzards of running too much pressure in the tires... and causing bruiseing??... This is new.. didn't know you could bruise a tire ... but indeed you can by over pressure for the load it is carrying.

Something new... Most tires will have a number for “Max.Cold Press.” embossed on their sidewalls.
Do not use this pressure in your tires! The proper air pressure will be on a plaque riveted inside the driver's front door. This is the car manufacturer's recommended pressure, based on the weight of the car and the tire size. (he is speaking of TV's here as they won't talk to you about trailer tires for some reason)
He contenued on.... we have seen that most think over pressuring the tires can help protect the wheels against impacts.
This is untrue, in fact, too much pressure can be as bad or worse than too little.
Stiffer tires will transmit more energy from an impact to the wheels/frame/ride than tires that are allowed to flex a bit.

He said that ..... If you do adjust the pressures.... watch your tires very carefully for signs of irregular wear. “Cupping”, or too much wear in the center of the tread, is a sign of over pressure for the load it is carrying. Too much wear to the shoulders of the tire is a sign of too little pressure for the load its carrying. Both cost you money and mileage.

When asked to speculate on max tire pressure... He said... Tire pressure that’s too high.... results in less tire touching the ground. (contact area)
In turn, this creates a harsher ride as well as compromised traction and the ability to stop quickly. A over pressured tire will not have the coeffecent ability to stop in less time... and will skid. A tire over inflated by as much as 6 psi can damag the tire more easily when tires run over potholes or debris.

Thus, Over time, over inflated tires lead to excessive inner tire tread wear, decreasing the overall life of tires.

He went on to say that close examination of the tire load/pressure chart provided by most manufactures is what one should go by and not just the MAX AIR PRESSURE on the tire sidewall when not needed.

Interesting... as I found this same though other places I inquired and searched.

BUT... now I have a question for ya...

When you change rims... and go to the sendels' or others... how much of the wheel stud should be past the rim boss... i.e how much should extend past the well of the rim for the wheel lug nuts to hold on to.

Some say that you only need the dia of the stud in length... others say you want at least 1/2 inch past the well. I.E at least 10 turns of the nut before it tightens down (our wheel studs are 20 tpi) .

I can't find any information on this subject... but clearly the alu rims have more meat in the lug area... so can this be a problem ?

Thanks again... G.M>

[CapriRacer]

Originally Posted by GM Airstream

...... Matter of fact he exp on the hazzards of running too much pressure in the tires... and causing bruiseing??... This is new.. didn't know you could bruise a tire ... but indeed you can by over pressure for the load it is carrying. .......

Allow me to explain.

Imagine a pyramid shaped object in the road and your tire is going to roll over it. If the tire pressure is low, then the tire envelopes the pyramid and rolls over it without damage.

But if the pressure is really high, the tire will try to climb it and the load on the tire will be concentrated at the peak of the pyramid. Enough pressure (and a large enough pyramid), and some of the cords will break.

How much pressure is too much pressure? Certainly the difference between 65 and 80 psi is OK. But the trend is there and it depends on the size and shape of the object. Some objects will cause problems even at normal pressures.

[DBinSD]

Originally Posted by Action

That article is about over the road tractor tires. The pressure range for those tires is a lot wider and the usage is much different. Hardly comparable to passenger, light truck or trailer tires.

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

I will point out that the article (as I mentioned to Tireman) was what lead me down the road of underinflation.

The statement in the 2016 Airstream manual pg. 8-8 "if a tire has been run in a 20% underinflated condition, it must be dismounted and inspected by a
trained professional"

Matches the statement by "The Rubber Industry Association strongly recommends demounting and inspecting a tire that has been run at less than 20 percent of the recommended inflation pressure."

The ambiguous part is getting the definition of UNDERINFLATION. Thus looking for that, the primary industry to try and define was the trucking industry. They "mostly" follow 20% (of cold inflation) is underinflated and 50% is flat and also applied to the radial tires as well.

Apparently SOMEONE knows about the underinflation definition in the passenger tire industry or the statement would not be in the AS manual as a CYA statement!

I have tried to provide written information on underinflation (reason for this part of the discussion).

From the NHTSA w/ regard to TPMS, appears to be the only "definition" using a number to define underinflation. "When the indicator illuminates, at least
one of your tires is more than 25% underinflated." The question is, 25% from WHAT? Sidewall, Placard? This number (25%) would seem to correlate to the above 20% definition for underinflation used for truckers and supported by the Rubber industry.

If anyone has information other than verbal opinion, please feel free to chime in. To me it seems the passenger tire industry is avoiding placing a number on underinflation. That would scream liability issues, IMO.

I submit the following question to ALL: Define underinflation for passenger tires with written statements.

[Action]

See post 48.

I don't believe there isn't a universal definition of what an underinflated condition is across the tire industry for all tire applications.

The over the road truck application may be the clearest definition to understand however to state that application can be applied to a ST tire application is not accurate. There is other tire data that isn't transferable between ST tires and P tires.

Since it is listed in the Airstream manual I would suggest contacting Airstream in the effort of getting clarity of the definition of under inflation as it pertains to that ST application or at least an Airstream trailer. And then post back here.

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

[mojo]

Originally Posted by GM Airstream

Something new... Most tires will have a number for “Max.Cold Press.” embossed on their sidewalls.
Do not use this pressure in your tires! The proper air pressure will be on a plaque riveted inside the driver's front door. This is the car manufacturer's recommended pressure, based on the weight of the car and the tire size. (he is speaking of TV's here as they won't talk to you about trailer tires for some reason)

Michelin and Nokian will not talk about the use of their tires (15") on trailers because they do not recommend passenger tires for trailer use. That is the response I received from both companies via email.

[DBinSD]

Originally Posted by Action

See post 48.

I don't believe there isn't a universal definition of what an underinflated condition is across the tire industry for all tire applications.

Since it is listed in the Airstream manual I would suggest contacting Airstream in the effort of getting clarity of the definition of under inflation as it pertains to that ST application or at least an Airstream trailer. And then post back here.

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

I saw and responded to post #48 from Tireman earlier.

My "quest" is to FIND the definition, as applies to passenger tires. Hopefully someone responds to the question with actual info we all can see/use.

I am trying to get a tire industry member to respond rather than AS. AS will only parrot what a manufacturer suggests. Mainly due to AS using both ST and LT tires while maintaining the statement.

Will update when I have something.

Thanks

[CapriRacer]

Originally Posted by DBinSD

........ I am trying to get a tire industry member to respond rather than AS. .......

Since this is all about definitions, I am curious what you think the definition of a "tire industry member" is. Doesn't Tireman9 qualify? How about me?

[DBinSD]

Originally Posted by CapriRacer

Since this is all about definitions, I am curious what you think the definition of a "tire industry member" is. Doesn't Tireman9 qualify? How about me?

Guys come on, no disrespect was ever intended.

What WAS meant by that comment;

I have reached out to Goodyear, Michelin and AirStream for a written SPECIFIC definition of under inflation.

Dan

[r carl]

Originally Posted by DBinSD

I saw and responded to post #48 from Tireman earlier.

My "quest" is to FIND the definition, as applies to passenger tires. Hopefully someone responds to the question with actual info we all can see/use.

I am trying to get a tire industry member to respond rather than AS. AS will only parrot what a manufacturer suggests. Mainly due to AS using both ST and LT tires while maintaining the statement.

Will update when I have something.

Thanks

I really think only ST or LT tires should be used on a camper. Possibly XL but never P rated tire.