Fiver tire pressure concern

[jadatis]

Play with the tabel I give here, In wich you are allowed to interpolate.

I would rather advice to set your highpressure allarm higher, so you wont get the alarm that soon.

NEVER BLEED AIR FROM A WARM TIRE.
So also never try to compensate the cold pressure to get a to your idea better warm pressure.

At that moment the tire needs that higher pressure to give the tire lesser deflection so lesser heatproduction.

When the vehicle maker determined their cold pressure , it was to give the tire , when warm, a pressure so deflection that wont overheat the rubber.

Once read from Tireman9 or Capriracer, dont know wich anymore, that tires have teststandards so they must be able to can stand a 2 to 3 times higher pressure then what is written behind AT.

Dont try this at home, but if you would fill your tires to 40% higher pressure then AT ( your 80 psi) at freesing temp of 32 degr F . Then if at some moment the temp in tire would rise to boiling point of water so 212 degr F. This pressure would rise to a small 2 times AT, and so still within the teststandards limits.

So dont be afraid of higher pressure then AT.

When you lowered the warm pressure , you gave the tire more deflection so more heatproduction, and by that the temp in tire rose to higher temp and by that the pressure rose a more % and inside tire temp came to even higher temp as in the unlowerd pressure situation, and set the alarm again.
And the temp in tire is releted to the temp of hottest part of rubber of tire, and that is what pressure-advice is all about, not to overheat the rubber when driving with loads and speed the advice is determined for .

Cold pressure is when inside tire temp = outside tire temp, that simple.
Tiremakers give cold pressure advice for 65/68 degr F and within a range the pressure chanches that little that you can neclect it.
But when verry cold or warm outside, you should calculate back the pressure you measure to that for 65 degr F.

Or ofcource use the list I give.

[grindstone01]

I have the same issue with my FW and TPMS readings. I find that my tires will gain 20 PSI+ when rolling. My G rated tires call for 110 PSI cold max which gives me readings of 130-135 PSI that I'm not comfortable with (potential bombs). My trials show that by running 10 PSI under cold max, 100 PSI, I will get TPMS readings of 120 PSI+/-. My scale weights show that the axles/tires are not overloaded w/G tires, OEM was E.

[tuffr2]

When I am traveling I air up in the morning to max cold tire pressure. No TPMS so I do not know how much pressure builds up as the tires get warm. But cold pressure is what the tire calls for so that is what I do.

[jadatis]

Originally Posted by grindstone01

I have the same issue with my FW and TMPS. I find that my tires will gain 20 PSI+ when rolling. My G rated tires call for 110 PSI cold max which gives me readings of 130-135 PSI that I'm not comfortable with (potential bombs). My trials show that by running 10 PSI under cold max, 100 PSI, I will get TMPS readings of 120 PSI+/-. My scale weights show that the axles/tires are not overloaded w/G tires, OEM was E.

Dont worry about the higher pressure , read my post directly above yours.
But your pressure rising is about 30% wich indicates a high inside tire temp. So you should review your cold pressure advice , probably to low for the loads and speed you use.
Or it must be that 110 is measured at 55 degr F and the 130/135 psi is measured when driving higher speed at outside temp of for instance 90 degr F .

If in normal conditions that 135 psi, you even should highen up the cold pressure of 110 psi to give lesser heatproduction so lesser inside tire temp so lesser rising in % of psi.
Then in the end the warm pressure could even be 140 psi , but then inside tire temp stays lower.

[Cumminsfan]

Originally Posted by tuffr2

When I am traveling I air up in the morning to max cold tire pressure. No TPMS so I do not know how much pressure builds up as the tires get warm. But cold pressure is what the tire calls for so that is what I do.

While I do have TPMS on the truck I don't on the 5er. I really don't care to have another gadget that makes things more confusing. I air up my truck tires to the needed weight to PSI ratio for my load, as well as my 5er tires to the PSI for the carried load.
I never check my tires on a trip. I may look at the 5er tires to see if they have some obvious problem but thats it.
When I put my 5er away for the winter in Oct and drag it out in March the tires are within a couple PSI of when I put it away.
I feel that if you're running the proper PSI and not overloaded running 75 mph down the road then you won't have any issues.
Been doing it this way for years.

[FastEagle]

IMO, on RV trailers, when TPMS setting for low pressure warning is set below vehicle manufacturer's recommended cold inflation pressures you are willing to travel with inflation pressures below the minimum required.

Tire inflation pressures can only be set when the tires are determined to be cold. Once thermal dynamics are in play you MUST rely on the tire's engineering to except those forces successfully. When in doubt, read the tire data book for the tire brand.

On page #34 in the following reference you will find this statement: "Never release pressure from a hot tire in order to reach the recommended cold tire inflation pressure. Normal driving causes tires to run hotter and inflation pressure to increase. If you reduce inflation pressure when your tires are hot, you may dangerously under inflate your tires. "

https://commercial.firestone.com/con...aBook_2016.pdf

[rarebear.nm]

That cold temp inflation adjustment table is a good thing to have- thanks.

[kcmusa]

My TPMS instructions say to set high pressure %20 greater than max cold inflation and low pressure %10 lower than max cold inflation. This has worked for me.
if I travel from a place and its 30 degrees I set my tires cold at this point. next day i am now at a place and its 60 degrees I set my tires again, cold.

[jadatis]

Originally Posted by Cumminsfan

While I do have TPMS on the truck I don't on the 5er. I really don't care to have another gadget that makes things more confusing. I air up my truck tires to the needed weight to PSI ratio for my load, as well as my 5er tires to the PSI for the carried load.
I never check my tires on a trip. I may look at the 5er tires to see if they have some obvious problem but thats it.
When I put my 5er away for the winter in Oct and drag it out in March the tires are within a couple PSI of when I put it away.
I feel that if you're running the proper PSI and not overloaded running 75 mph down the road then you won't have any issues.
Been doing it this way for years.

And thats the right way to handle, to my opinion.

I google dayly for tire-pressure, and nowadays 9 out of 10 hits is about TMPS.

People go worrying more about this system not working or overreacting , or how to get the light off again when it goes on, that it draws the attention from what is realy important.

And also here, TS and others see on their TMPS a high pressure, and lower them, while this is yust the wrong way.

In earlyer days they would not know so wont lower the pressure and tires stay save then.

Also every morning adjusting the pressure is not needed, once filled to the right determined cold pressure with some reserve(calculated back to 65 degr F) keep your hands off them, and check every 14 days or Month, and dont worry about it all and have a nice trip. You can still walk around the car and see if tires are not flat , and if so check the pressure, but mind what the temperature in tire is expected to be then.

And thats yust the way you handle .

[kedanie]

The OP most likely is running ST tires. Those tires are well known for running hot, hence all the instances of tread separations.

I would simply set the high pressure alarm 5 lbs higher and be done with it. Then just monitor the system for trends.

As for the low pressure, setting them for 10% low is correct. That 10% will catch a tire that may be loosing pressure while traveling. Checking them daily in the morning is not only easy but the correct thing to do. ST tires are well known for loosing pressure over a short time. Once one purchases a higher quality tire the loss of air pressure tends to go away.

Never bleed air from a hot tire!

Keith

[jacknife]

Just inflate your tires to manufactures specs and stop worrying about increased pressure. Carry two gauges and check if in doubt. Raise your TPMS Paramaters. You make something simple into a worrysome task.

[jacknife]

Low tire pressure develops more heat and weakens the integrity of the tire . Don't run you truck axle low or any doe that matter unless empty.

[Wundertaker]

We'll, safely at our site in heiskell....98 degrees !

A little clarification from yesterday. I do know to not bleed air from a hot tire...BUT, I did bleed each of mine 5 psi yesterday to get them down to "only" 10 psi OVER MAX COLD PSI PRESSURE.

Now for today, I changed my mind and set every tire at precisely max cold pressure except steer tires on one ton diesel which are set at 65 psi. All tires reacted similarly with none showing an anomaly. All tires, except steers, went up 9-12 psi with hot sunny ambient temps in high 80's. Tire temps never went over mid 90's so good there.

I'm going to call this a good learning experience as to how tires react under various weather and road conditions. BTW, I do have ST tires on my fiver.

Thank you to everyone for your help... I highly respect the guidance and opinions of those who've many more miles under their saddles!

THANX AGAIN!

[egwilly]

Great you worked it out!
I find having a TPMS on my fiver is a good safety item.... but, sometimes we chase the tire pressures around like a dog chasing his tail. Now I set 'em and forget "em.
Have fun!