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Old 04-17-2022, 08:55 AM   #41
CWtheMan
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Tire brands are not relevant for the vehicle manufacturers selections for original equipment tires. The OEM tires are selected for appropriate load capacity via the recommended cold inflation pressures.

The vehicle certification label is mandated by federal law and is a necessary step for the vehicle manufacturers to perform at vehicle certification time. You can look it up by typing 49 CFR part 567 into your search engine. ( https://ecfr.io/Title-49/Part-567 )
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Old 04-17-2022, 08:59 AM   #42
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Quote:
Originally Posted by Lil Joe View Post
I lost a wheel off of the 5er rolling down the interstate in Amarillo TX. The Tire Minder TPMS did not register anything. No heat build up, no disconnect. In fact it still showed I had correct pressure in that tire even though it had flown out into oblivion. We only noticed when the wife said the fender skirt was flapping. I called the company and they said."We'd be millionaires if we could figure it out to register if a tire went missing. So what good is it if one disconnects and the main monitor does not register it?
I never thought about my TPMS in those terms, but what I think you're saying is that if the ssensor reads decreasing pressure, it "reports that to the monitor which displays the information"... But if the sensor "disappears" the monitor just keeps on waiting for a signal.... Hmmmmm

I'm going to have to do some "experimenting this summer" to see if I can figure this out
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Old 04-17-2022, 09:10 AM   #43
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When I have time I'll need to look into this as well. Never thought about a tire/wheel separating from the trailer, figured I would know it. I also seem to remember disconnecting from the trailer and driving off with the monitor on and the numbers remained on the screen. Thought it was odd because I figured it would beep or something when it lost contact with the repeater. I'll have to refresh my memory and try that out to see what happens with this scenario in mind.

Lil Joe, I did not read back; what kind of TPMS do you have?
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Old 04-17-2022, 10:34 AM   #44
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Tires

Check the date code on tire. Ours were sitting for 2 years before the Rv was even thought of. Same here 2 tires blew on way to and from Tennessee. Went home and replaced all including spare with 8 ply Carlisle’s. That was the most ply in my tir size
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Old 04-17-2022, 12:47 PM   #45
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Originally Posted by Tireman9 View Post
My monitor holds a full charge for over a day of driving. While therr might be a claim of 2 or 3 days for monitor battery life, I simply shut the monitor off and plug it in for an overnight charge. Never had any monitor problems since 2010.
Following the above, each morning when I get up, I unplug the charger, turn the monitor back on and after starting my coffee I can go and get the morning, cold tire pressure reading to know that all tires have the desired pressure for that travel day.
Mine holds a charge for multiple days…. And I shut it off when done driving but I didnt pay attention that it needed to be recharged…was driving over 2700 miles round trip and it just slipped my mind until it went blank…I’ve been really happy with the performance but it needs regular charging…it wasn’t monitor problems it was human error
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Old 04-17-2022, 12:52 PM   #46
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Originally Posted by JRTJH View Post
I never thought about my TPMS in those terms, but what I think you're saying is that if the ssensor reads decreasing pressure, it "reports that to the monitor which displays the information"... But if the sensor "disappears" the monitor just keeps on waiting for a signal.... Hmmmmm

I'm going to have to do some "experimenting this summer" to see if I can figure this out
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Originally Posted by sourdough View Post
When I have time I'll need to look into this as well. Never thought about a tire/wheel separating from the trailer, figured I would know it. I also seem to remember disconnecting from the trailer and driving off with the monitor on and the numbers remained on the screen. Thought it was odd because I figured it would beep or something when it lost contact with the repeater. I'll have to refresh my memory and try that out to see what happens with this scenario in mind.

Lil Joe, I did not read back; what kind of TPMS do you have?

Well if that was the case …what happens when a battery goes dead in a sensor?…I believe it would time out after a few cycles of tpms checks and just register blank.
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Old 04-17-2022, 12:54 PM   #47
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Well I found the answer to a dead battery while driving and turned on..at least for the brand I have
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Old 04-17-2022, 02:01 PM   #48
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Quote:
Originally Posted by Lil Joe View Post
I lost a wheel off of the 5er rolling down the interstate in Amarillo TX. The Tire Minder TPMS did not register anything. No heat build up, no disconnect. In fact it still showed I had correct pressure in that tire even though it had flown out into oblivion. We only noticed when the wife said the fender skirt was flapping. I called the company and they said."We'd be millionaires if we could figure it out to register if a tire went missing. So what good is it if one disconnects and the main monitor does not register it?

With some systems the dash monitor can report a lost signal or bad battery but since the sensors only "report" about once every 10 to 15 minutes if there is no loss of pressure I don't know how any system can report a "lost" wheel without needing new batteries every couple of days.
If you have a question about this you can do a test yourself. Turn off the system. Wait about an hour then turn it on again. You will see it can take 10 to 15 or even 20 minutes before you get the reference psi reported.
As I understand it the sensors only report when there has been a pressure drop of x psi in the last couple of minutes. This "drop" is in your literature. The Tire Minder guy should have known this.




Comment to the folks that ever "lost a wheel" but didn't know it. This kind of proves the need for a TPMS as if you don't know when you loose a wheel now you can understand why it's possible to have a tire go flat you never know about it till someone flags you down.


My recommendation is to shut the monitor down each night and turn on back in the morning. If you don't get all tires reporting the cold tire pressure within 10 to 15 minutes you need to learn why.
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Old 04-18-2022, 03:59 AM   #49
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Quote:
Originally Posted by Tireman9 View Post
RVIA changed their requirements (Nov 2017 if i recall) to require tire inflation on the Certification label to be enough to support 110% of GAWR. But not all RV companies follow RVIA.
Are you saying that using the total weight of the towable divided by four plus a 10% cushion, should be the weight on each axle, and that you should adjust the tire pressure to what is called for by this number, based on the weight chart for that tire?

I wanted to make sure I understood you correctly.

That would put me at 7000/4 = 1850*110% = 1925 lbs for the weight per tire. The 7000lb is the GVWR. My actual weight, weighed on a scale, is around 5500 fully loaded for camping, but I'll use the max for this comparison.

With LRE ST225/75R15E Goodyear Endurance tires, that would put me at 45-50 psi instead of the max of 80?
https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

I changed to LR E tires from LR D when I replaced them a few years ago. Maybe I didn't need to? Interesting... Although the only tire Goodyear makes in my size is a LR E.

You can see in my sig that I have a TT older than 2017, so the sticker is the old style, but it still says to carry 65psi in the load range D tires that came with it. That is still overinflated, even by the tire manufacturers specs.
http://www.trailerkingtires.com/tire...2-product-line

I have been running my current tires(the Goodyears), at 70 psi, but it seems, according to this, that is overinflated, even for the max load the trailer can handle(GVWR).

Hmmm...

Edit:

Based on the 20-25% reserve capacity you talk about in your blogs, the China Bombs LR D at 65 psi(max psi) would be well over that reserve capacity. However, if they had been LR C, they would have been a little under at 50psi(max inflation), so that's probably why they were LR D.

Also based on the 20-25% reserve capacity, at 7000 lb, my current tires should be about 55 psi. At my "normal" camping weight of around 5500 lb, that could drop to around 40psi...

I have had a constant problem of the dealer over inflating the tires on my truck also. After an oil change at the Ford dealer, they are always at 44 psi, the max inflation psi on the tire. The door sticker says 35psi. The max weight rating for this tire is 2736 at 35psi. The tire has a max inflation psi of 44psi on the sidewall. I was not able to find a weight table for this tire, other than this tire appears to be at it's max weight rating at 35psi.
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Old 04-18-2022, 06:18 AM   #50
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Are you saying that using the total weight of the towable divided by four plus a 10% cushion, should be the weight on each axle, and that you should adjust the tire pressure to what is called for by this number, based on the weight chart for that tire?

I wanted to make sure I understood you correctly.

That would put me at 7000/4 = 1850*110% = 1925 lbs for the weight per tire. The 7000lb is the GVWR. My actual weight, weighed on a scale, is around 5500 fully loaded for camping, but I'll use the max for this comparison.

With LRE ST225/75R15E Goodyear Endurance tires, that would put me at 45-50 psi instead of the max of 80?
https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

I changed to LR E tires from LR D when I replaced them a few years ago. Maybe I didn't need to? Interesting... Although the only tire Goodyear makes in my size is a LR E.

You can see in my sig that I have a TT older than 2017, so the sticker is the old style, but it still says to carry 65psi in the load range D tires that came with it. That is still overinflated, even by the tire manufacturers specs.
http://www.trailerkingtires.com/tire...2-product-line

I have been running my current tires(the Goodyears), at 70 psi, but it seems, according to this, that is overinflated, even for the max load the trailer can handle(GVWR).

Hmmm...

Edit:

Based on the 20-25% reserve capacity you talk about in your blogs, the China Bombs LR D at 65 psi(max psi) would be well over that reserve capacity. However, if they had been LR C, they would have been a little under at 50psi(max inflation), so that's probably why they were LR D.

Also based on the 20-25% reserve capacity, at 7000 lb, my current tires should be about 55 psi. At my "normal" camping weight of around 5500 lb, that could drop to around 40psi...

I have had a constant problem of the dealer over inflating the tires on my truck also. After an oil change at the Ford dealer, they are always at 45 psi, the max inflation psi on the tire. The door sticker says 35psi. When I tried to explain to them that these same tires are used on trucks heavier than mine, I'm told that "all trucks need to be at the max tire pressure on the sidewall". HUH??? I don't go to that dealer anymore...

For trailers, Individual tire position weight is best as each axle end is probably not supporting 50% of the axle total


Individual axle weight is 2nd best as each axle is probably not supporting 50% of the total on both axles.


If you can't get individual axle end weight then I suggest calculating 52% for the "Heavy end".


The 20% reserve load is to address the "Interply Shear" found in trailer application.


Your TV should be inflated to door sticker. Have you confirmed the owner's manual does not have different inflation when towing?
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Old 04-18-2022, 06:48 AM   #51
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Thanks for your reply.

And I have checked the owners manual on the TV, and have not found anything that says a higher psi is needed when towing... I did find one section that said that the tire capacity would not be increased by an increase in tire pressure over 35psi...
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Old 04-18-2022, 07:53 AM   #52
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This subject of 'how much PSI should I run?' comes up frequently and is often confusing to me due to the breadth and scope of the answers. As I would venture many (most?) people with towables likely only know their total loaded weight - not per wheel or per axle, here is a simple question for Tireman:

If all I know is my trailer weighs a total of 8500 lbs fully loaded for camping, which is 1000 under GVWR, and my tires (per sidewall) are rated at 80PSI, and my trailer's placard also lists 80PSI.....

What should I inflate to?
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Old 04-18-2022, 08:49 AM   #53
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Well, I think tireman9 said it good in an earlier post.

Quote:
Originally Posted by Tireman9 View Post
Weight it. Learn the Minimum infl. Add 25%. Monitor inflation ALL THE TIME (TPMS). Inspect your tires at least once a year with a "Free-Spin" inspection. Go camping.
I have a lot of time on my hands to look up posts today because it's snowing heavily right now... The trailer is covered!
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Old 04-18-2022, 09:21 AM   #54
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Originally Posted by Stumpy75 View Post
Well, I think tireman9 said it good in an earlier post.



I have a lot of time on my hands to look up posts today because it's snowing heavily right now... The trailer is covered!
OK....so my ST22575R15 LREs are rated at 2,830 lbs @ 80 PSI

Wet trailer is 8500 lbs / 4 = 2,125 per tire x 25% = 2,656 per tire

Per the chart that’s 70-75 PSI. In my case at least, may as well just air 'em up to max.
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Old 04-18-2022, 10:34 AM   #55
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OK....so my ST22575R15 LREs are rated at 2,830 lbs @ 80 PSI

Wet trailer is 8500 lbs / 4 = 2,125 per tire x 25% = 2,656 per tire

Per the chart that’s 70-75 PSI. In my case at least, may as well just air 'em up to max.
Sounds right to me.

I have the same tires. ST225 75R15 LR E

My smaller trailer is 5500 lb / 4 = 1375 per tire *1.25 = 1718 lb per tire

That put me at around 40 psi per your chart. If I maxed the trailer's weight capacity out, I would be at 50 psi.

Sure wish Goodyear would have made that size tire in LR D, as even that is a little bit much for my smaller trailer. And LR C has just a little too small of a load rating.

Still snowing here. Brrr....
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Old 04-18-2022, 11:00 AM   #56
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Thanks for your reply.

And I have checked the owners manual on the TV, and have not found anything that says a higher psi is needed when towing... I did find one section that said that the tire capacity would not be increased by an increase in tire pressure over 35psi...



That means your TV tires are P type correct?
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Old 04-18-2022, 11:08 AM   #57
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This subject of 'how much PSI should I run?' comes up frequently and is often confusing to me due to the breadth and scope of the answers. As I would venture many (most?) people with towables likely only know their total loaded weight - not per wheel or per axle, here is a simple question for Tireman:

If all I know is my trailer weighs a total of 8500 lbs fully loaded for camping, which is 1000 under GVWR, and my tires (per sidewall) are rated at 80PSI, and my trailer's placard also lists 80PSI.....

What should I inflate to?

Well since you didn't provide the tire size I have to guess some things.

1. You do not have an actual truck scale weight because you gave a nice round 8,500 and 1000# figures so you are guessing.

2. GVWR includes tongue weight??? But IF the 4 tires are supporting 8500 excluding tongue weight then that would be theoretical 2125 each but more than likely you have axle to axle variation of about 53% PLUS uou may have end to end variation of maybe 52%

So heavy axle is 4505 and heavy end is 2342 So is that at least 15% under the tire max load? Not knowing your size I have no way to know how much load they carry at 80 psi

See what happens when you ask a question but don't provide the information really needed. I do cover the need to provide the important facts in my blog post of Feb 22 2012.


Sorry for this post being a little snippy but you are the 3rd person to ask similar question without providing the needed minimum information.
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Old 04-18-2022, 01:19 PM   #58
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That means your TV tires are P type correct?
Yes they are. Original equipment. My next set will be LT tires.

https://www.michelinman.com/auto/tir...lin-primacy-xc
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Old 04-18-2022, 03:59 PM   #59
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Well since you didn't provide the tire size I have to guess some things.

1. You do not have an actual truck scale weight because you gave a nice round 8,500 and 1000# figures so you are guessing.

2. GVWR includes tongue weight??? But IF the 4 tires are supporting 8500 excluding tongue weight then that would be theoretical 2125 each but more than likely you have axle to axle variation of about 53% PLUS uou may have end to end variation of maybe 52%

So heavy axle is 4505 and heavy end is 2342 So is that at least 15% under the tire max load? Not knowing your size I have no way to know how much load they carry at 80 psi

See what happens when you ask a question but don't provide the information really needed. I do cover the need to provide the important facts in my blog post of Feb 22 2012.


Sorry for this post being a little snippy but you are the 3rd person to ask similar question without providing the needed minimum information.
Tire size was provided in my next post (#54), prior to your reply.

I do not believe it's relevant whether or not my weight is CAT scaled or not (it was, but rounded), as my scenario is simply asking for a 'what if', my trailer weighs this much loaded and I have no idea what each axle/tire weighs. Doesn't matter if I tell you 8317 pounds or 9212....the formula to use, based on tire inflation charts, should be the same....that's what I'm trying to determine from your input.

As for tongue the weight....I am not sure what you are asking as far as 'is it part of my GVWR?'. I know what GVWR is and I know what tongue weight is and as CAT scaled I was just over 1200 lbs, based on 3 passes (with WDH active, with WDH bars off, and truck only) and my loaded trailer weight was in that 8500 lb ball park.

Excuse my snippiness, but I believe this is confusing, as the majority of experienced users simply tell you to load up, inflate to tire sidewall max PSI and don't exceed what is on the trailer placard....I'm just looking for a simplification for answering this when all that is known is the loaded weight of the trailer.
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Old 04-18-2022, 05:34 PM   #60
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Tire size was provided in my next post (#54), prior to your reply.

I do not believe it's relevant whether or not my weight is CAT scaled or not (it was, but rounded), as my scenario is simply asking for a 'what if', my trailer weighs this much loaded and I have no idea what each axle/tire weighs. Doesn't matter if I tell you 8317 pounds or 9212....the formula to use, based on tire inflation charts, should be the same....that's what I'm trying to determine from your input.

As for tongue the weight....I am not sure what you are asking as far as 'is it part of my GVWR?'. I know what GVWR is and I know what tongue weight is and as CAT scaled I was just over 1200 lbs, based on 3 passes (with WDH active, with WDH bars off, and truck only) and my loaded trailer weight was in that 8500 lb ball park.

Excuse my snippiness, but I believe this is confusing, as the majority of experienced users simply tell you to load up, inflate to tire sidewall max PSI and don't exceed what is on the trailer placard....I'm just looking for a simplification for answering this when all that is known is the loaded weight of the trailer.



If all you know is the trailer load on the tires (Truck scale reading) there are some things you want to consider.
If you assume incorrectly that all 4 tires carry the same load you could end up overloading one or more tires and not know it.
If you get the individual axles weighed than you can try assuming that one end is supporting 52% of the axle load from the truck scale. This may not be correct but it may prevent some overloading.


Once you plug the tire load figure into the Load/Inflation tables you can learn the MINIMUM cold inflation you should ever run.

Because of the unique Interply Shear forces trailers impart on the tires it would be to your advantage to ensure at least a +15% Reserve load with 20% being better. Do the simple math and learn how much air to put in your tires to get 115% or 120% of the measured load capacity. That inflation may be under the tire sidewall or sticker inflation number which is good. If you need more inflation than the tire sidewall or sticker number you need to run the tire sidewall number AND off load some stuff to lower your weight.


There is no simple formula to plug in the GVWR to give the needed inflation as there is more than simple static loading involved (Interply Shear)


The sticker identified the minimum inflation needed to support the GAWR assuming the weight is split side to side 50/50 which is unrealistic but that is what is done.


Actual scale weights of the load on each tire are the best way to learn how much air is needed as a minimum to support the measured load.


Since we know that over half of ALL RV's have a tire or axle in overload it is clear that most owners are not following the warning about overloading and under-inflation.


The primary reason for this is cost cutting as RVs do not come from the MFG with a 50% reserve load.. Also if there is space in the RV people fill the space with little thought on how much the stuff weighs.




8317 /4 = 2080 assume an out of balance between axle of 2% means one axle may be carrying 4323# and assuming one end of the heavier axle has 53% of that axle load then we are looking at 2292#


Your ST 225/75R15 LR-D need a minimum of 60 psi to support that load with no meaningful Reserve. If we want a 15% Reserve then 115% of 2292 = 2636# which suggests 75 psi in LR-D tires.


That's how you figure out what you need.
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