Good Sam Club Open Roads Forum: Another ‘dadgum’ post re: tire PSI…please bear with me…
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 > Another ‘dadgum’ post re: tire PSI…please bear with me…

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way2roll

Wilmington NC

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Posted: 11/29/19 07:10am Link  |  Quote  |  Print  |  Notify Moderator

goufgators wrote:

way2roll wrote:

Cold PSI means just that. Lowering PSI so the tires heat up to the recommended cold psi defeats the purpose of setting cold psi in the first place. They will be under inflated. As I am sure you are aware, low psi is the primary reason for tire failure - aside from a puncture. The F53 is notorious for poor handling. It's not going to handle like a car or a DP - ever. We had 2 gassers over the past decade and both were rather exhausting at the end of a long day in the saddle. Constant corrections. I would consider different tires, cheap handling fix or another model RV. Lowering psi below the tire manufacturers recommendation is not the proper way to handle the issue. You'd be borrowing risk. That of course is my opinion and I usually err to the side of caution. I am sure there are thousands of people out there driving on under inflated tires by 5 psi and either don't know it or don't care. I am confident however your tires will generate more heat.
I share your concern about under inflated tires but, knowing that they would be 'under inflated' for possible no more than 10 or 15 miles...I was just wondering if that would be enough time to damage the tires. I believe you're saying yes it would be inadvisable. Thanks for your comments.


I didn't mean to get all doom and gloom on you. Travelling all over the US, sure I check my tires prior to driving but if I am in a different elevation, dramatically different temp etc, if my tires are off by 5 psi I don't add air. Especially if I knew the conditions I were driving to would cause them now to be overly adjusted. Tires can survive a pretty wide range of psi and temps. The point I was trying to make is that I don't think knowingly adjusting PSI to lower than the tire manufacturer's chart doesn't seem to be the appropriate way to solve your problem, if it's a problem at all. Could be the nature of the beast. But no harm in trying and seeing for 20 miles. Do you have a TPMS?

And FWIW, I don't agree that the sticker in the MH is an accurate guide for setting PSI. Those stickers are put on at the factory and have no way of knowing how your rig is loaded for travel. Loading it and weighing is the only accurate way to know what they should be set to.

2chiefsRus

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Posted: 11/29/19 08:03am Link  |  Quote  |  Print  |  Notify Moderator

In your first post, you seem to discount the value of a four corner weighing. It really can identify issues that you may not be aware of that could be causing your problem. Also I agree with some of the other posters, tire pressure set too low is one of the primary cause of tire failure, along with the tires being overloaded.


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Octaneforce

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Posted: 11/29/19 10:09am Link  |  Quote  |  Print  |  Notify Moderator

What do you mean by front and rear stabilizers? Sway bars? The best thing i ever did for steering wander was a supersteer rear trac bar and 4 bilstien shocks. I also did 4 centramatic balancing rings which is supposed to lower tire temps. And to ice the cake, i measured my front swaybar diameter (mine is 1 1/4) and ordered universal poly swaybar bushings from energy suspension to replace the mushy rubber ones. It made head winds almost non exististent. I have a p30.

* This post was edited 11/29/19 10:17am by Octaneforce *


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goufgators

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Posted: 11/29/19 11:18am Link  |  Quote  |  Print  |  Notify Moderator

Octaneforce wrote:

What do you mean by front and rear stabilizers? Sway bars? The best thing i ever did for steering wander was a supersteer rear trac bar and 4 bilstien shocks. I also did 4 centramatic balancing rings which is supposed to lower tire temps. And to ice the cake, i measured my front swaybar diameter (mine is 1 1/4) and ordered universal poly swaybar bushings from energy suspension to replace the mushy rubber ones. It made head winds almost non exististent. I have a p30.
I might have meant sway bars rather than stabilizers. Please forgive me! That aside, thanks for identifying efforts you made to control steering. I may be able to use some of them. Again, thanks.


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ArchHoagland

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Posted: 11/29/19 12:50pm Link  |  Quote  |  Print  |  Notify Moderator

What size are your tires?


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Captain_Happy

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Posted: 11/29/19 05:06pm Link  |  Quote  |  Print  |  Notify Moderator

Something else to consider is inflating your tire with Nitrogen instead of pain air. Nitrogen doesn't heat up like plain air does. You stated that you F53 handles pretty good with PSI at 80 PSI when you start out, but as your tires heat up the handling changes. I've owned 2 F53 and they both handled badly.

Ductape

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Posted: 11/29/19 07:00pm Link  |  Quote  |  Print  |  Notify Moderator

FWIW the recommended inflation is for that weight at maximum rated speed. There’s no need to go that fast to test your hypothesis, drop the pressure five pounds and stay ten mph or more below the rated tire speed and don’t worry about it.


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2bzy2c

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Posted: 11/29/19 07:22pm Link  |  Quote  |  Print  |  Notify Moderator

Captain_Happy wrote:

Something else to consider is inflating your tire with Nitrogen instead of pain air. Nitrogen doesn't heat up like plain air does. You stated that you F53 handles pretty good with PSI at 80 PSI when you start out, but as your tires heat up the handling changes. I've owned 2 F53 and they both handled badly.



Bzzzzzt WRONG!

There is virtually no difference between N2, O2, Air and Co2 thermal expansion rates.

"I'll take Thermal Expansion for $100 Alex."


Geek speak on the subject -->

Ideal Gas Law: PV = nRT

This formula is the "Ideal Gas Law Formula." Although there is no such thing as an ideal gas the formula is pretty accurate for N2, CO2, and oxygen as we assume that the gas molecules are point masses and the collisions of the molecules are totally elastic. (A completely elastic collision means that the energy of the molecules before a collision equals the energy of the molecules after a collision, or, to put it another way, there is no attraction among the molecules.) The formula becomes less accurate as the gas becomes very compressed and as the temperature decreases but here "very compressed" pressures are well above even the highest tire pressures and "decreased temperatures" are extremely cold, too cold for tires. There are some correction factors for both of these factors for each gas to convert it to a Real Gas Law Formula, but the Ideal Gas Law is a good estimation of the way N2, CO2 and "air" should react through temperature changes. What does all this mean? It simply means that "air", nitrogen vapor, and CO2 vapor should all react pretty much the same within normal tire pressures (0-120 PSI) and temperatures.


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larry cad

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Posted: 11/30/19 12:38am Link  |  Quote  |  Print  |  Notify Moderator

The best thing I did to my coach to improve the wandering was the REMOVE the Steersafe that came with the coach. Before: wandered all over the road. After: steered straight down the road. I would never recommend them. Wore me out. I have a set in my garage if anyone wants it free!


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Octaneforce

Long island

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Posted: 11/30/19 02:57am Link  |  Quote  |  Print  |  Notify Moderator

2bzy2c wrote:

Captain_Happy wrote:

Something else to consider is inflating your tire with Nitrogen instead of pain air. Nitrogen doesn't heat up like plain air does. You stated that you F53 handles pretty good with PSI at 80 PSI when you start out, but as your tires heat up the handling changes. I've owned 2 F53 and they both handled badly.



Bzzzzzt WRONG!

There is virtually no difference between N2, O2, Air and Co2 thermal expansion rates.

"I'll take Thermal Expansion for $100 Alex."


Geek speak on the subject -->

Ideal Gas Law: PV = nRT

This formula is the "Ideal Gas Law Formula." Although there is no such thing as an ideal gas the formula is pretty accurate for N2, CO2, and oxygen as we assume that the gas molecules are point masses and the collisions of the molecules are totally elastic. (A completely elastic collision means that the energy of the molecules before a collision equals the energy of the molecules after a collision, or, to put it another way, there is no attraction among the molecules.) The formula becomes less accurate as the gas becomes very compressed and as the temperature decreases but here "very compressed" pressures are well above even the highest tire pressures and "decreased temperatures" are extremely cold, too cold for tires. There are some correction factors for both of these factors for each gas to convert it to a Real Gas Law Formula, but the Ideal Gas Law is a good estimation of the way N2, CO2 and "air" should react through temperature changes. What does all this mean? It simply means that "air", nitrogen vapor, and CO2 vapor should all react pretty much the same within normal tire pressures (0-120 PSI) and temperatures.


In the hvac business we use nitrogen for leak down tests under the assumption that it doesn't fluctuate in pressure like compressed air will. However we use pressure way beyond that of a tire (500-600psi). I guess this is within the theory you provided.

Why do race car drivers bother to use nitrogen in their tires? Is it a myth?

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