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Old 05-19-2013, 08:09 PM   #21
CWtheMan
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Originally Posted by iamrwnut View Post
Looks like I am going to have to hit the scales to find out my true weights, then adjust my tire pressure accordingly.
Here is a “what if” for you. Lets say your trailer came with OEM 15” tires. The 65 psi on the tire placard indicates they were LRD. If your current tires are in fact 16” and the same design as the OEM tires than the 65 psi would still be valid. If the new tires are 16” LT tires the correct tire pressure for them is the amount of pressure it takes to equal the load capacity of the OEM tires at 65 psi.

CW

p.s. Remember, tire manufacturers DO NOT set vehicle tire pressures. Vehicle manufacturers do.
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Old 05-19-2013, 08:23 PM   #22
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Another FYI. We purchased from a dealer not a private owner so no way to know when they were replaced.
Maxxis is the only ST tire manufacturer that I have found that will allow their tires to be manipulated with air pressure below the maximum sidewall pressure without invalidating their warranty.

Maxxis canned answer is it’s OK with them as long as it’s approved by the vehicle manufacturer.

You can call Mr. Shawn Brennan - east coast Maxxis rep - at 687-404-6772 for conformation on that.

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Old 05-19-2013, 08:32 PM   #23
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For reasons unknown to me, tire manufacturers are often reluctant to print industry standards. Industry standards are normally a combination of government regulations and inputs from contributing agencies such as the RMA or T&RA.

By DOT regulation the manufacturer of your RV trailer is tasked with determining and setting the correct tire pressure for your Original Equipment (OE) tires. The correct tire pressure is depicted on the trailer’s federal certification label and is depicted as the recommended cold tire pressure.

Industry standards will not violate those recommended pressures for your OE tires or replacements of the same size and load capacity. When replacements are different in size and/or design new recommended tire pressures will be determined by the installer. The information for determining the new recommended pressures will be determined using the amount of load capacity the OE tires provide by their recommended pressure.

In the reference provided below you will see the emphasis placed on the words; “NEVER use inflation pressures lower than those printed on the vehicle placard.” That’s a reinforcement of an industry standard.

http://www.trucktires.com/bridgeston.../WeighForm.pdf

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Old 05-19-2013, 08:52 PM   #24
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This can be debated forever. I will say that in over 200,000 towing miles with ST tires the only tire issues have been a few repairable nail punctures.

AND

I have not yet inflated a TT tire to the max on the sidewall. I use the designers tables, plus 5 psi for luck. Note I DO know the weights of each tire.

Must admit I have never used Chinese tires. Some say that is not meaningful, and MAYBE they are right, but it works for me. I also do not run tires over 7 years old per DOT code.
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Old 05-19-2013, 11:06 PM   #25
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This can be debated forever. I will say that in over 200,000 towing miles with ST tires the only tire issues have been a few repairable nail punctures.

AND

I have not yet inflated a TT tire to the max on the sidewall. I use the designers tables, plus 5 psi for luck. Note I DO know the weights of each tire.

Must admit I have never used Chinese tires. Some say that is not meaningful, and MAYBE they are right, but it works for me. I also do not run tires over 7 years old per DOT code.
I’ve seen a number of your posts and I’m pretty sure you’re using Maxxis tires.

When the tire industry talks about the correct or recommended (cold) tire pressure they are referring to the recommendations found on your trailers certification label or tire placard.

Some people are very successful operating outside of the established standards. You are obviously one of them and I’ve left your posts alone in the past because you’re so adamant about it.

Here is a link to the Maxxis trailer tire warranty. It does not cover tires under or over inflated or overloaded.

http://www.maxxis.com/Industrial/Tra...-Warranty.aspx

I’ve talked with Mr. Sawn Brennan (Maxxis tire rep) about tire pressures for the Maxxis trailer tires. Maxxis supports the trailer manufacturers tire pressure recommendations 100%.

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Old 05-20-2013, 06:34 AM   #26
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Originally Posted by CWtheMan View Post
When the tire industry talks about the correct or recommended (cold) tire pressure they are referring to the recommendations found on your trailers certification label or tire placard.
My truck has a genuine placard, showing four different pressures for the two axles, loaded and empty. The figures were calculated by a bona fide automotive engineer and reflect actual loads.

My trailer, on the other hand, has a sticker that simply indicates the OEM tire's sidewall pressure for all four tires. While I applaud the trailer industry for conveying the fact that the sidewall pressure is usually the correct pressure, absolutely zero engineering went into this labeling.

While trailer tire pressure is not as load sensitive as LT tire pressure, there still must be some adjustment based on actual load---which could vary by 1000 pounds per tire. RVSEF clearly recognizes this.

So I find the statement that "Maxxis supports the trailer manufacturers tire pressure recommendations 100%" extremely disappointing.
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Old 05-20-2013, 11:00 PM   #27
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The certification label/tire placard regulations are basically the same. However, the method used is also based on the regulations and they differ dramatically for the automotive industry as compared to the RV trailer industry. Reserve tire load capacity is not required - by regulations - for the RV trailer industry. It is required - in two parts - for the automotive industry.

That often confuses many RV trailer owners that have never had to deal with those tire pressure differences.

The Special Trailer tire (ST) is universally manufactured to be operated at their maximum allowed tire pressure. Because their manufacturer’s build the tires for the RV trailer industry there is an unwritten understanding that the RV trailer manufacturer will use the maximum sidewall pressures on the trailer’s certification label and tire placard. It’s a two fold safety valve for the trailer builder. One; they are taking advantage of the maximum load capacity to set GAWR and GVWR. Two; They are insuring the owners are going to have the necessary load capacity up to and including the full GAWR. Beyond that is not their responsibility.

CW

p.s. Remember, the vehicle manufacturer - by DOT regulations - has the sole responsibility for setting the recommended cold tire pressures found on the vehicle’s placarding.
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Old 05-21-2013, 06:52 AM   #28
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Regarding previous statements in this thread that tire manufacturers universally recommend inflating to the maximum psi molded into the sidewall, I found the following statement on the Bridgestone website referenced by CWtheMan:

"Always determine correct tire inflation pressure based on actual loads on the tires. Use the tiremakers’ recommendations (which you will find in load and inflation tables)."

Clearly, if Bridgestone was recommending inflating to maximum psi, this is where they would say that rather than saying to find your psi in the load and inflation tables.

Furthermore, Maxxis on their website does not say to always inflate to max psi. Instead they also provide a load and inflation table to use to determine proper psi.

Regarding, the previous post that points to the Maxxis warranty excluding under-inflated tires, I believe Maxxis would consider a tire to be under-inflated if the psi was less than the recommended value listed in their load and inflation table. I do not think Maxxis would consider a tire to be under-inflated just because it was inflated to less than the max psi.
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Old 05-21-2013, 07:26 AM   #29
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Originally Posted by gepaine View Post
Regarding previous statements in this thread that tire manufacturers universally recommend inflating to the maximum psi molded into the sidewall, I found the following statement on the Bridgestone website referenced by CWtheMan:

"Always determine correct tire inflation pressure based on actual loads on the tires. Use the tiremakers’ recommendations (which you will find in load and inflation tables)."

Clearly, if Bridgestone was recommending inflating to maximum psi, this is where they would say that rather than saying to find your psi in the load and inflation tables.

Furthermore, Maxxis on their website does not say to always inflate to max psi. Instead they also provide a load and inflation table to use to determine proper psi.

Regarding, the previous post that points to the Maxxis warranty excluding under-inflated tires, I believe Maxxis would consider a tire to be under-inflated if the psi was less than the recommended value listed in their load and inflation table. I do not think Maxxis would consider a tire to be under-inflated just because it was inflated to less than the max psi.
Consider this scenario for a moment. Let's say I was heading out for 10 days of dry camping and for this particular trip I would need to load up the 5th wheel more than usual. For example, the FW tank might be filled rather than empty, propane tanks topped up and extra food and clothing thrown in as well. In the truck, I've added a generator, wood and a few other items which would normally not be taken along.

All of this extra stuff in the RV and truck adds to and obviously changes the load on the tires. For argument's sake, let's say there was an additional 500 pounds added - 350 to the RV and 150 to the truck.

Prior to this last increased load, I am running the tires at 10 psi lower than the recommended psi based on the data in the tables - not the recommended psi stamped on the tire.

Question - Because of the new increased weight of the RV and the truck, should I head to the scales, reweigh everything, refer to the tables and adjust the pressure in both the TV and the 5th wheel tires before heading out?
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Old 05-21-2013, 07:51 AM   #30
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Festus2,
That seems to be the general consensus of this thread. Adding to your scenario, after having used the firewood and the water and the food and the propane; does that mean you should re-weigh your rig and reduce your air pressure before heading home?
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Old 05-21-2013, 07:52 AM   #31
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Just a question, not a hijack.. Someone posted a link on one of the tire threads to the manufacture that provides aluminum wheels for Keystone. Would someone please repost that link. I can't seem to find it.

Thanks

Edit

A call to Keystone answered my question. The aluminum wheels used by Keystone are manufactured by Tredit. They have a page that shows all of the wheels they sell. Click on one and it will give you the load rating for that wheel. it does not give the PSI rating, but a call to them gave me an answer of 80PSI for my particular wheel. A check on a couple of their steel, spoke type wheels shows PSI ratings that are significantly lower than the aluminum wheels until you get into the 16" wheels, so I think that if anyone is planning to upgrade to a higher load range tire, a call to them might be the prudent thing to do.

http://www.tredittire.com/Aluminum-Wheels-C10.aspx
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Old 05-21-2013, 08:14 AM   #32
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Of course, you don't do all those trips to the scale! (Unless you are super anal!) I think you weigh once while loaded for your typical trip and determine the proper psi from the load and inflation table provided by the tire manufacturer. Then add 10-15 psi to that value (but not to exceed max psi), air your tires to that psi, and forget about it. The extra 10-15 psi should handle variations in your load.
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Old 05-21-2013, 09:01 AM   #33
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Thanks. Not being anal, I won't be making multiple trips to the scales. I did, however, follow up on Bob's post and also phoned Tredit - the folks that made the wheels on the 5th. I gave them the info stamped on the wheel and asked them if it was good for 80 psi. He also asked if it was steel or aluminum and when I told him it was a steel wheel, he said it would be fine to run the tire at 80 psi. From that, I take it that aluminum wheels may not have as high a load rating or psi capability as a steel one ???

But Tredit's saying that the wheel is capable of safely handling 80 psi answers my concern about running the Maxxis at 80 psi - the recommended pressure.
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Old 05-21-2013, 09:36 AM   #34
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Me thinks some folks are being a bit anal....

In the majority of cases the manufacturer isn't putting tires that exceed the necessary load by any appreciable margin, therefore running them at the maximum pressure isn't a bad thing... I'd way more worried about overloading the whole thing including the axles than running the tires at max pressure...
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Old 05-21-2013, 09:41 AM   #35
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Have to agree. I think too many people have too much time on their hands. I think just about everyone would agree that running tire pressure at max gets the greatest longevity on drivable vehicles. Why would the same not hold true for travel trailer tires. More inflation, less rubber hitting the ground, less heat generated, longer tire life.. What am I missing?
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Old 05-21-2013, 11:02 AM   #36
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Bob and Festus2,

You have convinced me that it is time for me to stop participating in this thread for fear of being accused of having too much time on my hands. (I wonder, does that apply to everyone that participates on this forum or only to those you disagree with?)

Just to be clear, I have no problem with people who choose to run at max psi. I just can't find anything on the web (such as at RVSEF, the Maxxis website, the Bridgestone website, etc.) that says it's bad to run at the psi that is recommended in the tire manufacturers load and inflation tables.

Bye
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Old 05-21-2013, 11:36 AM   #37
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The teacher made me write this on the blackboard ....

"I promise not to submit any more posts in this thread."
"I promise not to submit any more posts in this thread."
"I promise ......."

Only 98 more to go.
But when I'm finished and have more time on my hands, then what will I do?
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Old 05-21-2013, 11:46 AM   #38
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The teacher made me write this on the blackboard ....

"I promise not to submit any more posts in this thread."
"I promise not to submit any more posts in this thread."
"I promise ......."

Only 98 more to go.
But when I'm finished and have more time on my hands, then what will I do?
Keep posting. I appreciate your knowledge and insight. Much of the input from the administrators of this forum is great information. John, Hank, Steve and yourself, Festus, do a great job. I feel fortunate to have found this group, I don't have to re-invent the wheel. I may not always like some of the answers, but at least they are rooted in experience.
As for being anal about certain things, I'm as guilty as they come, especially if I think I am right based on my own personal experience. Obstinate and down right thick headed may be a more accurate description.
Keep doing what you do.

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Old 05-21-2013, 11:51 AM   #39
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Now Festus, you're just being anal.
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Old 05-21-2013, 12:04 PM   #40
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Now Festus, you're just being anal.
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