Tire Pressure Vs. Ambient

[bluwtr49]

I recently found that adjusting our tires to the cold inflation temperature base on the local ambient may not be the correct way to do this. Based on this info, the ambient temp for setting tire pressure is always 65F and they are than adjusted upwards base on local ambient.

This was a surprise to me and would suggest that many are running their tires under inflated.

Tire Pressue vs Ambient

Something to consider. Me, I'm going to follow this guide.

[Executive45]

wolfe10 wrote:

the_vfox wrote:

Executive wrote:
Damn, now I've got to sit here until the temp drops to 65 degrees...gonna be a long summer I guess...:B....Dennis

Its worse for us, it has to warm up to 65 :W

NO, that is the good news in the summer.

Headed your way SOON!

How are you gonna get OUT of Texas without a BOAT.....:h....Dennis

[holstein13]

This is exactly the way Triptek programs their tire pressure sensors in my RV. It's based on temperature and pressure so if the temperature rises, the TPMS system calls for higher pressures in the tires. The base temperature is at 65 degrees.

I love the system because it tells me if I'm above or below the ideal pressure and I can inflate my tires at any time. I just turn to the proper tire screen and fill or release as needed. That's a huge benefit for me. I don't have to wait until morning to inflate my tires. I can inflate them first thing in the morning, at noon when the sun is shining on them or after skidding to a halt in 100 degree weather. It doesn't matter. My TPMS calculates it for me.

Once you've had the pleasure of getting the heat adjusted tire pressures, you won't want to go back to the old way of checking pressures in the morning only.

[wolfe10]

the_vfox wrote:

Executive wrote:
Damn, now I've got to sit here until the temp drops to 65 degrees...gonna be a long summer I guess...:B....Dennis

Its worse for us, it has to warm up to 65 :W

NO, that is the good news in the summer.

Headed your way SOON!

[the_vfox]

Executive wrote:
Damn, now I've got to sit here until the temp drops to 65 degrees...gonna be a long summer I guess...:B....Dennis

Its worse for us, it has to warm up to 65 :W

[Executive45]

Damn, now I've got to sit here until the temp drops to 65 degrees...gonna be a long summer I guess...:B....Dennis

[pconroy328]

wolfe10 wrote:
Wow, two of us who remember our school physics/chemistry at the same time.

It's worse for me. As a Biochem major my head is filled with completely useless (and perhaps no longer valid) cr*p like Selenium deficiency and exudative diathesis. Or the carbon tracking on the Krebs cycle.




But I can't remember where I parked the car.

[wolfe10]

Wow, two of us who remember our school physics/chemistry at the same time.

[wolfe10]

bluwtr49 wrote:


On the other hand, it's right on the money based on my current ambient (90F) since the pressures have risen 5 psig and it was about 65F last time I adjusted the pressures.

Yes, the ideal gas law applies. For a given rise in Temperature, there WILL be a specific rise in Pressure. PV=nRT has been around for a LONG time.

Same basic physics that prove some of the ads for Nitrogen in tires are so much bunk. Nitrogen, like other gases DOES follow the ideal gas law, not "Bubba's marketing law 101".

[pconroy328]

Never mind the fact that most of use pressure gauges with absolutely no idea of their accuracy or precision. While the physics may be sound, PV = nRT, it strikes me as needless hand-wringing and worrying.

"Gee, it's 72* outside, let me check the conversion chart... OK, now I'll pull out my $3 pressure gauge and check..."

[wolfe10]

Campfire Time wrote:

wolfe10 wrote:

Sure looks like another of those "if you read it on the Internet........" things.

And he's probably a French model too. Bonjour. 😉

Oui, Oui. Or in Texas we would just say, Wee Wee.

[rgatijnet1]

I wonder why the chart DOES NOT follow it's own rule at the bottom that says:
Tire manufacturers never recommend inflating a tire to less than the specified cold inflation pressure. The bead of an RV/commercial tire can unseat
if its pressure gets too low resulting in a catastrophic tire failure. The general rule of thumb is to inflate a tire to a proportionately higher starting value when the ambient tire/temperature is hotter than 65 degrees and to the recommended Cold Inflation Pressure value at temperatures below 65
degrees F.

The chart then shows that at a recommended cold inflation pressure of 100psi, or any psi, if the temp drops to 32 degrees, it says you should inflate to less than the recommended cold inflation pressure. If it followed it's own advice, the chart would stop at 65 degrees. :R

[Campfire_Time]

wolfe10 wrote:

Sure looks like another of those "if you read it on the Internet........" things.

And he's probably a French model too. Bonjour. 😉

[fla-gypsy]

This is what Maxxis says about inflation of the tires I use;

"...In order to accurately assess your tires’ inflation pressure, please note that inflation pressure should be adjusted and/or checked when the tire is cold or before driving for the day."

I call BS on the 65* baloney and adjusting for temperature.

[bluwtr49]

Yeh, I have my suspicions also not knowing the providence of the chart.

On the other hand, it's right on the money based on my current ambient (90F) since the pressures have risen 5 psig and it was about 65F last time I adjusted the pressures.

I'm thinking I will use the chart since I can not see any harm. For example, I will be leaving when the temps are ~104 and within 3 days be in 60F temps. Worst case, be a little high but no chance of being low.

[rgatijnet1]

So you want to go with an "anonymous" tire inflation chart with no idea who came up with this theory and something that is not endorsed by any tire manufacturer?
Me, I'm going to follow the tire manufacturer's charts.