sorry but I am new to this: ...80PSI????

[tireman9]

So Tireman9, even though the GVW weight of my coach is well below what 4 of my G614's can handle (maximum load each of 3750 @ 110psi ), from what you are saying, I should just keep them set at 110 psi and not worry about the load charts? And if my rims are stamped "110psi", should they have enough of a tolerance built into them to handle the psi fluxuation of the tire (as it heats up and cools down) if I am at 110 psi "cold"? I am leaning towards running them at 110 psi and monitoring them more often.

The rep I spoke with at Good Year encouraged me to run them at 110psi, regardless of load, and from what I gathered in your earlier post, you are saying the same thing.

If so, I know it will require me to monitor the psi more often, but I am good with that as long as I will be able to limit tire issues!

Lets see. Your tire placard says 110psi. The Goodyear Rep says 110. I say 110 (I never worked for Goodyear)
Maybe you could try 110

Yes there is enough tolerance built into tires & wheels to tolerate changes in pressure and temperature due to people driving on the tires.
The assumption is that the tires started out the trip not overloaded.
The tires were NOT driven above their max speed rating which is 75 for most RV applications except 65 for ST type tires. ( there are a small number of exceptions but the 65 or 75 is probably 98% of tires)

The inflation for trailers was set to the pressure molded on the tire sidewall associated with the max load
The tire gauge is accurate to +/- 5% or less variation
The tires had not been driven on or in sunlight for two hours prior to checking the pressure.

A TPMS is the only reasonable way to monitor tires as you travel as there is no way to know if you picked up a nail jsut after leaving the campground, fuel stop or rest stop.

 

[Jim.Allison]

Increasing the pressure beyond the 80 psi on my TV pushes my OEM TPMS to its limits. RAM says to inflate to 60 psi front and 75 rear under load. I run 60 and 80. 80 is the max sidewall. If I run 85 psi and then get out on a Texas highway on a 105 degree day, my OEM TPMS will creep up beyond 93 psi, and then show a random number that is obviously not a tire pressure reading.

Perhaps running a cold tire pressure at 90 which would be 10 psi over the sidewall pressure, the tire would run cooler but surely the TPMS would again climb over 93 psi and quit displaying the pressure.

What say Tireman9

 

[jnbhobe]

Why does your TPMS quit above 93* ??

 

[Jim.Allison]

This is the RAM Truck OEM TPMS system that does this , my rigs TPMS has no problem.

I dont know, I guess I should research it beyond what I have. But the owners manual speaks to the issue. I just assumed that I was running more than the 75 psi specified on the door post and under high temps that the 93 psi was the limit of the TPMS. 93 is the last psi shown above that it gives a 4 digit number that is clearly not a pressure reading in any unit of measurement.

Why does your TPMS quit above 93* ??

 

[tireman9]

Increasing the pressure beyond the 80 psi on my TV pushes my OEM TPMS to its limits. RAM says to inflate to 60 psi front and 75 rear under load. I run 60 and 80. 80 is the max sidewall. If I run 85 psi and then get out on a Texas highway on a 105 degree day, my OEM TPMS will creep up beyond 93 psi, and then show a random number that is obviously not a tire pressure reading.

Perhaps running a cold tire pressure at 90 which would be 10 psi over the sidewall pressure, the tire would run cooler but surely the TPMS would again climb over 93 psi and quit displaying the pressure.

What say Tireman9

You didn't say what your tire size or Load Range was But if it is something like LT235/85R16 LR-E then the sidewall of the tire probably says 80PSI at max load and your tire placard says 75 when loaded. Why are you over inflating your tires?

Who told you it was a good idea to rum more than the sidewall cold pressure? Since your TPM doesn't like pressures above 93 maybe it is telling you something about over inflating your tires also. Pressure only increases about 2% for each 10F increase. Yoy are seeing a 24% increase in pressure over what your truck mfg says is correct. Something is way off if you are running 100F or more hotter than ambient. Overload or high speed.

You should set your tire pressure at Ambient temperature. Not when they are in the sun or have been driven on in the previous two hours. Are you sure your tire gauge is accurate? I have posts on pressure gauge accuracy too. I use a Digital gauge that is available from Amazon or Sears for $10 to $13.

I have numerous posts on my blog on pressure and temperature

Another reason for big pressure increase is the tires are inflated with wet air. If you let air out of your tires do you get any spits of water?

 

[Jim.Allison]

I mis read an earlier post, referring to 10 psi over sidewall, my reason for the post was to explain that I could never inflate my tires to 10 psi over. Sorry for the confusion. But rest assured that I do not intend to inflate to over 80 psi for any reason. And I do have the digital tire gauge.

But reading your response does clear it up for me. RAM has the TPM set fairly tight. It does not take much to exceed the TPM capability.

I did some quick calculations and determined that just a few neglected items can run tire pressures up quickly. Even though I have the digital gauge you mentioned, I have never calibrated it. I dont even know how close the TPM is to the gauge. I do need to install a dryer on my compressor, I know there is no water in my tires but there will be if I don't put the dryer on. And lastly vigilance on cold pressure readings. The pillar pressure is what the TPM expects to see, if you are inflated to 80 psi, then you are already 5 psi toward that 93 psi where the TPM is going to quit.

I understand that the higher pressure tires increase in pressure more like 2 lbs per 10 degrees. I used 1.5 for my work here.

But this beckons two more questions. When should you check the cold pressure reading? After loading or before loading? And if I do run the 75 psi on the door pillar as opposed to the 80 psi on teh sidewall how much load will I be giving up if any?

You didn't say what your tire size or Load Range was But if it is something like LT235/85R16 LR-E then the sidewall of the tire probably says 80PSI at max load and your tire placard says 75 when loaded. Why are you over inflating your tires?

Who told you it was a good idea to rum more than the sidewall cold pressure? Since your TPM doesn't like pressures above 93 maybe it is telling you something about over inflating your tires also. Pressure only increases about 2% for each 10F increase. Yoy are seeing a 24% increase in pressure over what your truck mfg says is correct. Something is way off if you are running 100F or more hotter than ambient. Overload or high speed.

You should set your tire pressure at Ambient temperature. Not when they are in the sun or have been driven on in the previous two hours. Are you sure your tire gauge is accurate? I have posts on pressure gauge accuracy too. I use a Digital gauge that is available from Amazon or Sears for $10 to $13.

I have numerous posts on my blog on pressure and temperature

Another reason for big pressure increase is the tires are inflated with wet air. If you let air out of your tires do you get any spits of water?

 

[tireman9]

Jim
What post did you mis-read on adding 10psi? I would like to go back and clarify it.

 

[Jim.Allison]

Just read #20, its 10% anyway not 10 lbs.

But now, since I added up all the variables, I see how quickly tire pressures rise and why. I never stopped to evaluate this process but now that I have, I am suprised.

Jim
What post did you mis-read on adding 10psi? I would like to go back and clarify it.