Tire pressure during cold mornings warm afternoons?

[bclinton]

Curious.....what do you folks do with fluctuating pressures with temp swings. As an example I try to ready everything days ahead and check pressures. When I check them the pressure is fine (around 82 per tire). The morning I leave we have a cold front come through and the pressures are 5-6 pounds lower all around. Do you worry about that small change and just drive on? The reason I ask is that it is no easy task airing them up on the rears. I have to remove the wheel simulators to get to one of the tires.

[TriGlide]

I set the pressure in my 335DS Georgetown at the 92psi that is shown on the sticker in the unit and go on...It usually in the 70's when I do it and then I run them all year without problems . I live in KC Mo so it gets cold here also. I have never had a problem in the 5 years that I have been doing it...

[PodGeek]

I've had this question as well. Here's an informative link that I just dug up:

https://www.tirerack.com/tires/tiret....jsp?techid=73

[Iggy]

I set 378TS 22.5" tires to 90 psi in front of my house in Arizona.
I'm at 1,000 ft elevation and tempurture is about 80 degrees.

After on the highway thay all rise higher depending on where I'm going.
Palm Springs CA in the summer is hot and the 90 psi can rise to 109 psi easily.

Now if I go into Utah where its a higher altitude the may all stay about 95psi but if I stop for the night and have a cool night the tires ususally drop to 86 to 87 psi.

I just drive out of the park and by the time I hit the highway they usally get back up to 90 psi and then start rising from there depending on the type of roadway, speed and outside air temps.

So to answer your question I still monitor them and try to stay at 90 psi and usually do not add and pressure for my travels.
A few pounds 3 psi + - couldn't be a problem unlesss you are in cold climate all the time. Then you need to set them up at 90 psi fo rthe normal outside temps.

If you use the number on the wall plaque is fine as long as you monitor regually as I do with a Tire Pressur eMonitoring System.

[bubbles]

I make it a point to check my MH tire pressures at least once a year. Have not had any issues and anyway the tires are changed about every 7 years (regardless the mileage) and have never had any issues between tire changes on any MH owned over the past 20 years.

[The Evil Twin]

Like the tires on the truck‐ I check/ adjust when I have the time. If they are around what they should be, I don't mess with them. As long as they are within 5psi I call it good. From 30 degree mornings to 70 in the afternoon. They will only fluctuate 4 or 5 psi.

[NXR]

I ascribe to the philosophy that you should inflate motorhome tires to the correct pressure for the load and add 10% so you're not chasing pressures. For us "load" is close enough to the 90 PSI on the sticker that I use 90 as the minimum and usually inflate to 98 to 100. My maximum cold pressure stamped on the sidewall is 110 PSI so I'm well away from that when "cold".

So far I need to add air twice a year, Fall and Spring, and then only about four or five PSI.

I recently filled them around 70 degrees F and when it got down into the mid-30's as it does overnight sometimes, the tires are at 90 or 91 per the TPMS.

Remember, a tire that is 20% underinflated is considered flat by all major tire manufacturers and susceptible to internal damage. Had I filled to 90 and then they dropped to 82, I would be halfway to flat. 82 actually is where I have the TPMS Low Pressure alarm set.

Ray

[NXR]

Originally Posted by PodGeek

I've had this question as well. Here's an informative link that I just dug up:

https://www.tirerack.com/tires/tiret....jsp?techid=73

One caveat on that article is this paragraph:

The rule of thumb is for every 10° Fahrenheit change in air temperature, tire pressures will change about 2% (up with higher temperatures and down with lower). This means that light-duty, standard-pressure tires (typically inflated to 30-50 psi) used in applications on cars, vans and light trucks will change by about 1 psi; where heavy-duty, high-pressure tires (typically inflated to 80-100 psi) used in applications on recreational vehicles, busses and trucks will change by about 2 psi.


The remainder of the article is written from the perspective of light-duty car tires, not truck/RV tires. So adjust their numbers accordingly.

Ray

[Jim34RL]

With AL wheels you need to check more often than steel wheels. I check once a month usually in the afternoon, but out of direct sunlight on the tires. I air the tires up according to the manufacturer weight tire inflation tables, published by the tire manufactures. I do this on both my truck, my wife's car and the trailer during the camping season.

I never have to adjusted the air pressure in my tires do to cool mornings temps.

[jadatis]

Once a good tire-pressure is set, with enaugh reserve to inacurate pressure-measurement, and misyudging of real weight on tires, checking is OK, but dont go chanching it, for every temperature and hight.

Pressure advice is to prevent any part of tire from overheating, when driving the maximum speed constantly, for wich it is determined.

Advice pressure is given for an ambiënt temp of 65 degr F. ( some write 68 degrF, but difference in pressure is that little, so not worth the discussion, even 70 degrF).
Also for sea-level so 14.7 psi/1013 mb ambiënt pressure.

When colder ambiënt temp, lower pressure in tire, so more deflection, so more heatproduction at same speed, but also better cooling down by larger temp-differences between critical temp of rubber and in- and outside-tire gascompound( air Nitrogen or whatever)

Hotter ambiënt temp the other way around, lesser heatproduction by lesser deflection, but lesser cooling down.

So within a certain range of ambiënt temp, the pressure is right when calculated back to 65 degrF.

Once read the suggesion, that absolute pressure counts for deflection( so heatproduction) so even in vacuüm ambiënt pressure , you dont have to fill up or let pressure of.

What you measure is overpressure above the ambiënt pressure.
So if you have on a certain hight a ambiënt pressure of 5 psi lower( 9.7 psi) , you have to fill your tires to 5 psi more overpressure then determined needed pressure, to give it the same absolute pressure.

Not the complete story, because at higher overpressure a little more expansion of tire, so then on sealevel a tiny bit more pressure then determined needed ( will be less then 1 psi)

Enaugh for now to absorb

[Dodge Guy]

Set tires to cold pressure for your particular weight and tire size. I check mine a couple days before I leave and monitor them with the TPMS. Some morning they will be a few psi lower. After about 15min in the highway they are where they should be.