Extreme cold tire pressures.

[haydoracin]

Took a trip in September and checked tire pressures before during and after trip and all pressures were correct. Didn't have to add air since last trip in fall of 2012. Checked pressures today and all were equal but were about 7 psi below what they were in September. Could this be due to the extreme cold (-10 to -20) we have had recently or should I bring them up to what I normally run?

Thanks,

Haydo

[wolfe10]

Correct-- Nitrogen and DRY air follow the same laws of physics and PSI change with temperature change is the same.

But, moisture in tires (from a compressor with no dryer) does NOT follow those gas laws so more PSI change with temperature change.

[wolfe10]

Correct-- Nitrogen and DRY air follow the same laws of physics and PSI change with temperature change is the same.

But, moisture in tires (from a compressor with no dryer) does NOT follow those gas laws so more PSI change with temperature change.

[Effy]

sailor_lou wrote:

Effy wrote:
I was told Nitrogen eliminates this. Apparently it's also more dense than air so there is no loss. Anyone know for sure?

The ideal gas laws apply to nitrogen as well as to air, which BTW is composed of 80% nitrogen, so even nitrogen filled tires will be impacted by temperature. Also, FWIW nitrogen is actually slightly less dense than air (1.25 kg/m3 vs 1.29 kg/m3 at Standard Temp & Press).

Lou
05 Travel Supreme Envoy

Thanks. I failed chemistry. 🙂

[sailor_lou]

Effy wrote:
I was told Nitrogen eliminates this. Apparently it's also more dense than air so there is no loss. Anyone know for sure?

The ideal gas laws apply to nitrogen as well as to air, which BTW is composed of 80% nitrogen, so even nitrogen filled tires will be impacted by temperature. Also, FWIW nitrogen is actually slightly less dense than air (1.25 kg/m3 vs 1.29 kg/m3 at Standard Temp & Press).

Lou
05 Travel Supreme Envoy

[Effy]

I was told Nitrogen eliminates this. Apparently it's also more dense than air so there is no loss. Anyone know for sure?

[Dutch_12078]

I aired up all my tires to my normal cold settings in Upstate NY at about 10 deg F before leaving for Florida last month. When we got to South Carolina with temps in the 50's, I had to drop about 6-7 PSI from each tire to get them back down to my cold settings. I hope when we head back north in April, it'll be warm enough up there that I won't have to air them back up again! :E :B

[wolfe10]

Yes, temperature has a marked effect on PSI.

If you will be driving on those cold temperatures, yes air them up to your regular PSI.

If you will be driving shortly with warmer temperatures, no need to do anything.

If you will be parked for a month or longer, Michelin's advice is to air the tires to max on sidewall as long as it does not exceed rim limits. Then reduce to "driving PSI" when you get ready to hit the road.

[rgatijnet1]

If you plan on driving, you need to bring them up to your normal PSI. "Cold" tire pressure is defined as the tire pressure before you start driving for the day. There is no set "cold" temperature as very big temperature swings and high altitudes will all affect the tire pressure at the start of a drive.

[LynnandCarol]

yes, it probably is. We had something like this happen we were in a cold snap in Louisiania.