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Old 05-03-2014, 06:55 PM   #21
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To those that think they can learn the individual tire loading here are some facts from a recent weighing of a new Class-A.
LF 5632 RF 5254 LR 10,284 RR 11,308

So you can see it is not correct to take the axle weight and divide by 2

TT have similar side to side unbalance in addition to axle to axle imbalance when there are two or more axles involved.
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Old 05-03-2014, 07:02 PM   #22
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I had to do axle/2. So I followed the GY recommendation and used the heavier one to determine the proper inflation. There are a couple of folks in TX that have access to individual wheel weights for the same unit (36CKTS) and as expected, the Left Front was the heavy.

Individual wheel load info would be great but you also have to have some flexibility there as your load changes way to frequently to try to use nano psi increments. Even the pressure gauge has a variable. Reason would dictate that +/- 4psi would be "close enough for government work" but I personally would tend to err on the high side.
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Old 05-08-2014, 11:49 AM   #23
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Originally Posted by Duckogram View Post
BigJohnD
I had to do axle/2. So I followed the GY recommendation and used the heavier one to determine the proper inflation. There are a couple of folks in TX that have access to individual wheel weights for the same unit (36CKTS) and as expected, the Left Front was the heavy.

Individual wheel load info would be great but you also have to have some flexibility there as your load changes way to frequently to try to use nano psi increments. Even the pressure gauge has a variable. Reason would dictate that +/- 4psi would be "close enough for government work" but I personally would tend to err on the high side.

My recommendation for Motorhomes is to get the individual corner loads. Use a worksheet as seen here if you can't find individual scales. Once you know the actual loads when your RV is fully loaded use the heaviest end of each axle and load/inflation tables from the tire brand you are using (a small % of tires do not follow industry standards) to learn the MINIMUM cold inflation.
Use a digital pressure gauge (I have found these more accurate than the sliding stick type) inflate your tires to the minimum +10%.
Use a TPMS if you want to get a warning if/when you get a puncture or valve leak.

Trailers should still get the individual tire loads to learn which are overloaded. trailer load is seldom 50/50 between axles and almost never 50/50 side to side. The inflation for multi axle trailers is easy. Use the inflation on the tires. You should of course back check the load capacity at the max inflation with the actual loads and have a 15% margin or you can expect much shorter tire life. A TPMS is good for trailer owners too as tou will seldom feel the tire going flat.
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Old 05-08-2014, 01:55 PM   #24
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It was brought to my attention that a post from someone on the list I mentioned earlier and an outspoken proponent of the blow hard (maximum inflation) group has quoted me and posted a contradictory statement. I was given a reference posted by that person so I checked it out.
Here's the reference: http://www.trucktires.com/bridgeston.../WeighForm.pdf
So I expected to find support for blow hard but to my amazement, the reference
fully supports determining the actual load and using the tire manufacturers
recommended pressures for that load. Of course it does say to never exceed the max inflation pressure stamped on the tire...
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Old 05-08-2014, 02:14 PM   #25
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Quote:
Originally Posted by Duckogram View Post
It was brought to my attention that a post from someone on the list I mentioned earlier and an outspoken proponent of the blow hard (maximum inflation) group has quoted me and posted a contradictory statement. I was given a reference posted by that person so I checked it out.
Here's the reference: http://www.trucktires.com/bridgeston.../WeighForm.pdf
So I expected to find support for blow hard but to my amazement, the reference
fully supports determining the actual load and using the tire manufacturers
recommended pressures for that load. Of course it does say to never exceed the max inflation pressure stamped on the tire...
Ducky, I have to be honest- I'm not sure what you're saying with this post.

On edit, it seems you're saying that Tireman9 is on your blocked list.

You think he's posted contradictory information - in one post he says to use maximum inflation for the tires but linked to a bridgestone document that says to use load inflation tables.

Maybe.
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Old 05-08-2014, 02:48 PM   #26
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Ducky, I have to be honest- I'm not sure what you're saying with this post.

On edit, it seems you're saying that Tireman9 is on your blocked list.

You think he's posted contradictory information - in one post he says to use maximum inflation for the tires but linked to a bridgestone document that says to use load inflation tables.

Maybe.

And, if that IS the case- you're being awfully contradictory to your comment earlier:

Quote:
Originally Posted by Duckogram View Post
I also respect the opinion of others if it is not claptrap or argumentative.

You've literally posted solely to take a pot shot at Tireman9 and be argumentative.

Pick one way or the other, man- he's either on your "every growing ignore list" or he isn't.
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Old 05-08-2014, 11:07 PM   #27
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It appears there is some confusion about my recommendation on inflation.

In my post, #23, I said "Motorhomes" can use actual load and adjust inflation accordingly. The link under motorhomes, suggests adjusting the inflation based on the actual tire loads so I see no problems.

I make a different recommendation for trailers. Based on engineering analysis multi-axle trailers have different tire needs and therefor have different inflation recommendation. That being to run the inflation on the tire sidewall. i.e. the "Max Inflation".

To help clarify I will offer this link for weighing trailers. Here you will see the same recommendation I make to run trailer tires at max inflation. You will note the procedure to learn individual tire loads is the same as in the other link. The difference is that this web site is aimed at a different market. i.e. trailers.

For those that were confused I apologize for not making two different posts. I have learned that unless I make the two part statement one about Motorhomes and the 2nd about trailers some people may do just a quick read and make an incorrect assumption that I am saying that all RVs should run max pressure, or that all RVs should adjust for load, which of course I am not.

As a tire engineer I try and not make the broad generalized statements that others may be comfortable with but try and be specific.
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Old 05-08-2014, 11:33 PM   #28
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Here's the way I see it at the end of this round:
Tireman 1
Ducky 0
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Old 05-08-2014, 11:39 PM   #29
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General inflation recommendations.

Based on testing of over 50 gauges used by RV owners Digital are the most likely to be accurate and the sliding stick type the least accurate. Here is a post on one group of gages.

If you have a motorhome and can set your inflation based on actual individual tire load I suggest you establish an minimum cold inflation and add 10% to learn the target inflation when setting the cold inflation. This 10% means you are not chasing your tail every time the ambient temperature changes 10F.

If trailers adjust their load to be at least 15% below the tire capacity, that will give them some flexibility in day to day variation in cold inflation but they should aim toward the tire max so they can lower the inter-ply shear that is trying to tear the tread and belts off the tire body ply.

Checking your tires every couple of hours is fine and dandy as long as you believe you can never run over a nail or develop a valve leak except just before you stop to check your tires. Here is a post of a Blowout that occurred even though the driver had checked the tire just a couple of hours earlier. I have over 20 posts on "Blowouts" with many identifying the reason for the failure.
The best way to minimize Blowout due to run low flex is with a TPMS. More than one person has recovered the cost os a system the first Summer of use by avoiding the failure or learning about the puncture early enough to avoid damage to their trailer.
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Old 05-08-2014, 11:57 PM   #30
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Quote:
Originally Posted by GOTTOYS View Post
Here's the way I see it at the end of this round:
Tireman 1
Ducky 0
Of course you do. But this is not an argument between two members to be scored. It is about G614 LT tires on a Cedar Creek.

So I took the time to read the posts and followed the references.
Then I researched the authors of both. With actual data considered and resources evaluated by credibility, I chose to go with the tire manufacturer(s). If I were running ST's I would be a blow hard proponent as well. But that is not the subject.
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