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Old 06-03-2016, 08:40 AM   #41
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your the expert, the video on their web site says that you set the low pressure warning to 10 psi below the set psi, and the high 20 psi above the set pressure,

https://youtu.be/5-KsnSUM2F8

now if your set psi is 90 and the max tire pressure on the side wall says 100psi, and then the temperature exceeds the max pressure of the side wall, then I am not understanding, if the tire can handle a max pressure of 175 psi, why do they have it stamped on the sidewall 100, as you can see I am not a tire expert, I need to read more about this pressure stuff on your site I guess, thanks for the info

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Originally Posted by Tireman9 View Post
Thanks for the additional info. Lets set aside the pressure measurement question and assume the tires were set to 90.

You said you set the tires low at 80 or high at 110. I do not understand why. With a motorhome you should always have the tires set to no less than the minimum pressure needed to support the heavier end of each axle based on actual measurements. I have covered this a number of times in my blog. I also recommend that cold inflation pressure be set to that minimum inflation +10% and rounded up to the next 5 or 10 psi increment to make measurement and remembering pressure easier.

We know that if we follow the math of 'Gas Law" that tire pressure will change about 2% for each change of 10F. So if your tires were running at Ambient + the normal 20 to 60F range in temperatures, we could expect a 4% to 12% increase ion pressure. I have seen some reports of a pressure increase of as much as 15% but that is the exception in my experience and may be a function of improper load measurement or higher operating speed.

A review of the TST manual shows the high pressure warning to be at 175 psi from factory so have no idea why your unit is giving a high pressure warning at 110psi as you said in post #36.

RE tire capability. Your LR-G tires should handle 175psi with no problem as long as they have not been damages, run with low inflation or improperly repaired.

Suggestions:
1. Set the high pressure warning to 175 psi
2. Confirm your measured loads and that 90psi is at least 10% greater than the minimum shown for the measured load per the information in the Load tables.
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Old 06-03-2016, 10:33 AM   #42
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Quote:
Originally Posted by hammer55 View Post
your the expert, the video on their web site says that you set the low pressure warning to 10 psi below the set psi, and the high 20 psi above the set pressure,

https://youtu.be/5-KsnSUM2F8

now if your set psi is 90 and the max tire pressure on the side wall says 100psi, and then the temperature exceeds the max pressure of the side wall, then I am not understanding, if the tire can handle a max pressure of 175 psi, why do they have it stamped on the sidewall 100, as you can see I am not a tire expert, I need to read more about this pressure stuff on your site I guess, thanks for the info
I watched the video and I do not agree with the suggestion to set the low pressure warning below the pressure needed to support the load. This could result is driving on an overloaded tire for days which could do damage.

I do suggest you review my blog for more details and background on tire load and inflation, I also have a post on Minimum vs Maximum inflation.

But the short answer is
Set the low pressure warning on the TPMS to the minimum pressure needed to support the measured load.

Select your cold "set" pressure to that minimum +10% and round up to next 5 or 10 psi. So if you need 80 to support the load your set pressure would be 88 rounded to 90. If you needed 85 to carry the load the set pressure would be 94 rounded to 95

I am more concerned with high temperature than high pressure as tires are designed to tolerate pressure increase due to operation. Most TPMS use 70c or 158F as the high temperature warning level and I am comfortable with that.

With your truck tires, I would be comfortable with a pressure increase of 25 or maybe 30 psi
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Old 06-03-2016, 02:29 PM   #43
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If you are comfortable with a max pressure increase of 30 for his tires, why tell him to set the high pressure at 175? You are confusing even more than usual.

The 100 psi rating for your tire is the maximum cold tire inflation number, in your case above for 68 degrees. Tires are designed to handle an increase beyond this pressure when heated up. I have never seen a tire company publish exactly what 'beyond' means, but a 10-20 percent increase could probably be considered normal. A combination of sun, rolling resistence, and ambient temperature increase all influence the temperature increase in your tire and hence the pressure increase. You tire is not going to blow at 110 and I would be surprised if you see it that high very often.


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Old 06-03-2016, 03:20 PM   #44
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Quote:
Originally Posted by lbrjet View Post
If you are comfortable with a max pressure increase of 30 for his tires, why tell him to set the high pressure at 175? You are confusing even more than usual.

The 100 psi rating for your tire is the maximum cold tire inflation number, in your case above for 68 degrees. Tires are designed to handle an increase beyond this pressure when heated up. I have never seen a tire company publish exactly what 'beyond' means, but a 10-20 percent increase could probably be considered normal. A combination of sun, rolling resistence, and ambient temperature increase all influence the temperature increase in your tire and hence the pressure increase. You tire is not going to blow at 110 and I would be surprised if you see it that high very often.


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Point I am trying to make is that they can set the high pressure warning much higher than the 110 as suggested by TST in their Mar 27 2012 video. I have no idea what TST was thinking about by suggesting that running under-inflated when they instruct users to set the low pressure warning at 10 psi below the tire set pressure". I also do not know why the High pressure TST suggested resulted in a warning signal.

I see little reason for any high pressure warning as I do not know how you can get that without already exceeding the high temperature warning of 158F.

I have contacted Hammer55 and offered to call and talk them through tire pressure setting.


There are a number of posts on this forum I have written outling exactly how to learn what pressure to set your tires to and what to set the TPMS at. I also have over 200 posts on my blog with probably over 40% having something to do with load and pressure.

I seem to keep writing the same advice over and over as apparently people are not willing to do a few basic searches on this or other similar forums and look at the qualifications of the poster to see if the questions they have are already answered.

I have also contacted TST and asked what they were basing their pressure warnings on.

I do not understand your reference to 68 degrees in my example. It does not matter what the ambient temperature is. If you have established you need xx psi to support your measured load and you have added my suggested margin the resulting number is the pressure I would suggest for your tire set pressure. There are no calculations or further adjustments of pressure that are based on ambient temperature.

Note my 100 psi example is not the inflation I am suggesting for hammer55 but just an example for calculation example.

I do get a bit frustrated at time. I know that if I write something someone will more than likely take information out of context and they may end up having a tire failure.

This information should be provided by evert RV dealer but it isn't. GY and Michelin each have RV specific publications and even video on RV tire inflation but again few seem willing to read these information books. I have traveled across the US at my own expense offering seminars on RV tire application and I spend many hours each week responding to questions on a number of RV forums. Just this morning I even contacted Tire Rack and pointed out another error I discovered in the web site.

Sometimes the wife asks why I bother. Sometimes I agree and wonder.
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Old 06-03-2016, 03:51 PM   #45
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The first sentence was for you Tireman and the rest for for the poster you suggested 175 degrees to. He set his 100 lb max tires at cold 68 degrees. Maybe you have to many threads in your brain to remember 2 hours ago.


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Old 06-03-2016, 04:01 PM   #46
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TST hung up on me twice ?

New info.
Just heard back from TST. Twice they hung up on me because the blog I write, that is owned and run by RVTravel.com has a competitor TPMS company as a sponsor.

It is their position that I am bias so they are not willing to discuss, in a civil manner, the question of why they are advising customers set the high and low pressure warning to "-10psi and +20 psi".
What is interesting is that the first person I talked with, before I identified myself as a tire engineer and that I write a blog on RTire Safety, insisted that the video said -10% and +20% and that even -30% was reasonable in hot temperatures.
She was reasonable and asked for my name and number so someone could call me back to discuss the question.

It was a man that called back. said he thought my "Tiretraker blog was nice looking" but he had no interest in talking with a competitor and immediately hung up on me before I could say a word,

I returned his call and he said that because I "worked for a competitor" I was bias and again hung up on me.

IMO TST appears to not be interested in helping customers understand proper setting of their TPMS if they would have to talk with a tire engineer that writes a blog that is posted on a site owned and run by another individual.

Maybe my hearing is off. When I listen to the Youtube
https://youtu.be/5-KsnSUM2F8
at about 3:16 and again at 3:50 I seem to hear advise to set the the pressures to a psi not a percent.

But maybe because I don't work for TST my hearing must be off.
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Old 06-03-2016, 05:18 PM   #47
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Tire pressure monitor systems

The high pressure on my Tire Traker from the manual is 25 percent. The max I have reached is 22 percent so that alarm has never sounded so I don't know if it actually works. The manual says 15 percent on low pressure and I have tested that this works.


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Old 06-03-2016, 05:26 PM   #48
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When I set mine up I set the psi to 68.3 (instead of 65) so it would would alarm at 58 instead of 55 which is closer to 10 percent.


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Old 06-03-2016, 07:40 PM   #49
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Blog Sponsor issue

In response to Tireman and the TST dispute. I guess my first question is do you work for, or are you associated with Tire Traker in any way? Do you feel any obligation to Tire Traker? I went to your site to see what may have made the TST folks question your call. At the top of your site is a massive banner that says "This Blog is Sponsored by Tire Traker". IF you are going to be a nuetral party then you may want to drop the sponsorship, or at least go with sponsors not directly associated with what you are disputing on your posts. Im not saying that to be ugly, I happen to think your blog is useful, but getting into it with other TPMS systems in a public forum when you are sponsored by Tire Traker just doesnt seem cool. If you follow TPMS then you have to know that TST is a leader in this space.
Having said that, I believe all TPMS say to set your parameters above and below the suggested cold tire rating. Is anyone suggesting that if the exact number the tire should be at is 90 psi then that is where the low parameter is? The alarm would be driving you nuts on cold mornings.
Anyway, RVing is supposed to be fun, this post is a bit stressful, I think I will move on to another one.
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Old 06-03-2016, 09:31 PM   #50
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typo in post $46
-30 should be +30
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