Rise in tire pressure

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Joined
Jan 5, 2021
Messages
16
Location
Woodstock, GA
RV Year
2021
RV Make
Keystone
RV Model
Cougar 364BHL
RV Length
39’ 3”
Fulltimer
No
How much rise in psi is too much? Pulling about 13,000 lbs fifth wheel. Max tire psi is 80. I‘ve taken 2 short trips and the tires are at 80 psi (which is where the dealer said we should set them). The Hughes they have gotten is 89 psi. I have a tpms. Just wondering what is normal.
 
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Nov 2, 2019
Messages
3,615
Location
WA, MT or somewhere else!
RV Year
2018
RV Make
Newmar
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Mountain Aire 4047
RV Length
40'
TOW/TOAD
2020 Lincoln Nautilus or 2014 Honda CR-V
It is “normal” for tire pressure to increase due to temperature rise. “Maximum PSI” is a cold-tire number. The pressure rise due to temperature is calculated in by the tire designer. As long as (a) you stay at or below the rated maximum inflation when the tire is cold, (b) are not loading the tire beyond its rated capacity and (c) are running the tire at the recommended inflation for the load, you will be fine. Increases of 10-12 PSI due to temperature rise are quite “normal.”

It is always a good idea to get side-to-side axle weights of your travel-ready RV (full water tank, propane tank, etc.) and consult the tire manufacturer’s inflation charts for the appropriate pressure to run. RV manufacturers usually do this in their initial calculations and post the appropriate inflation pressure in their product.

The only caution is to be sure that you have not overloaded your 5th wheel by loading more cargo in than it was designed to carry.

TJ
 
Joined
Jan 5, 2021
Messages
16
Location
Woodstock, GA
RV Year
2021
RV Make
Keystone
RV Model
Cougar 364BHL
RV Length
39’ 3”
Fulltimer
No
Thanks TJ. I’m using the Vesafe tpms, and the default for psi is 1.2X for the alert. If I’m at 80 cold, is 96 way too high for the alert or is that about the time to worry? Also, I’m driving around 65 on the freeway for speeds. I believe the tires rating is 80.
 
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Colorado
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2016
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Newmar
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Ventana
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2020 Jeep Cherokee
For the motorhome I generally see ~8-10lbs pressure increase. My front tires are set at 100psi. On a hot day (90+F) I'll see +10lbs. Rears are set at 90 and I'll see similar gain.
 
Joined
Nov 2, 2019
Messages
3,615
Location
WA, MT or somewhere else!
RV Year
2018
RV Make
Newmar
RV Model
Mountain Aire 4047
RV Length
40'
TOW/TOAD
2020 Lincoln Nautilus or 2014 Honda CR-V
Thanks TJ. I’m using the Vesafe tpms, and the default for psi is 1.2X for the alert. If I’m at 80 cold, is 96 way too high for the alert or is that about the time to worry? Also, I’m driving around 65 on the freeway for speeds. I believe the tires rating is 80.
I think that default setting is fine; it wouldn’t worry me at all.

TJ
 
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Frostproof, Florida
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Heartland
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Cyclone 4006
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2021 F350 DRW
Fulltimer
Yes
The outside temperature, your load, your speed, and having sun shinning on your tires all play a part in how much the psi will increase going down the road. From everything I have read almost all tires will certainly blow out when their temps reach 165 or above.

I have a little different tires and rims on my fiver and run 105 psi. If I were running 80psi I would set my high limit at maybe 96 or 100 and my high limit temperature at 140 or so. If your system has a low limit psi setting I would keep it around 72 to 74 because on a 35 degree morning they could register close to that when heading out.
 
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Florida
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CanyonStar
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Demco KarKaddy 460SS and VW Passat
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No
Just as a point of reference. The 20% programmed in as a Default is about correct. You don’t want false signals. If you have an issue temps will rise reasonably rapidly and you will get a warning at psi cold plus 20%.
I made the mistake of adjusting mine diwn to cold plus 15% and triggered a warning going into Death Valley. There was no issue but dealing with that alarm while negotiating the road out of the mountains into the valley was a PIA I didn’t need just then😊
 
Joined
Jan 5, 2021
Messages
16
Location
Woodstock, GA
RV Year
2021
RV Make
Keystone
RV Model
Cougar 364BHL
RV Length
39’ 3”
Fulltimer
No
Thanks for all the help. This is exactly what I was looking for. This will help me keep a good eye on the tires and keep my sanity!
 
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