Changes in Air Temp and Tire PSI

[RobWNY]

If airing up tires to 80 PSI (Manufacturer recommended Max cold pressure indicated on tire) while air temp is 45 degrees and then traveling to a warm climate, will I likely have to let some air out? What I'm getting at is this....I start out with air temps at 45 degrees, tires at 80 PSI. I travel to where the air temp is 80 degrees. From past experience here in the Northeast, I know that my tire PSI in the summer when traveling gets to near 100 PSI when air temps are in the 80's and remain around that temperature for the duration of my trip. But now, I'll be airing up tires to 80 PSI and going from a cool air temperature to a warm temperature along with hot tires from traveling. From what I've read, tire pressure increases about 2% for each 10 degree increase in temperature. Using that as a guide, my tire pressure will be in the neighborhood of 105-110 PSI. Should I start out at something less than 80 PSI or is this something I shouldn't be overly concerned with?

[Campinfan]

Gonzo42 wrote:
As a rule of thumb, air pressure in tires incraase about one psi for a temperature increase of 10 degrees F.

Tire pressure should be set when cold. That is such as first thing in the morning or when the tires have not been running for at least 3 hours. The settings specified assume an ambient temperature of about 72 deg F.

If the air temp you have is different, you can make a calculation such as: if ambient temperature is 52 deg F, reduce your pressure by 2 psi.

I concur. I had to study tires for Crash Reconstruction. Air them up cold to the sidewall amount. The tires are made so that when they warm up and the air pressure increases, it will be fine.

[RambleOnNW]

Cold inflation pressure refers to ambient temperature at the time you are driving not the cool of the morning. An added factor is highways with sun shining on them adds additional heating. I usually inflate my rear duals to around 76-77 psi in the morning to target a cold inflation pressure of 80 psi at drive time and that produces a hot driving temperature of 88 psi as read out by the TPMS monitor. Pressure rise is around 1.5 psi for 10 degrees F.

[ktmrfs]

philh wrote:
Pure nitrogen has ZERO advantage in car/truck/trailer tires.

Negligible yes, Zero, not quite. Nitrogen molecules are larger than Oxygen (even though atomic weight is less) so pressure drop over time due to the fact that tires aren't completely "air tight". Now to start with even with "regular" air your already at 80% nitrogen.

And since the process of getting pure nitrogen eliminates any water vapor there is less pressure variation due to changes in water vapor content.

The later can be solved by using an dry air source.

However, IMHO in the end unless it is free, offers no advantage worth paying for in consumer applications.

[Campinghoss]

I run 110 in my G tires all the time. I only check the psi before leaving a cg or home regardless of the temp. Sometimes folks can sweat things that really don't need to be worried about. I always check when cold.

[philh]

Pure nitrogen has ZERO advantage in car/truck/trailer tires.

[JimK-NY]

ajriding wrote:

......
So, what happens if a tire is deflated a little bit?

......

Tires flex and build up heat which increases the pressure and decreases the flexing. If you lower the pressure the tire is going to flex excessively which will shorten its life and if severe enough will cause a failure.

[ajriding]

JimK-NY wrote:

Absolutely, not fine and very dangerous advice. Never, ever deflate a hot tire because the pressure increases due to driving. If it is hot and you are carrying a heavy load at high speed, the solution is to slow down. Even then expect high pressure during highway driving in hot weather.

Maybe so. I never deflate tires in middle of drive so do not know. The tire should be able to handle being heated up and the increased psi that goes with it.
So, what happens if a tire is deflated a little bit?

pizza-oven guy, 115 deg is hot to walk around in all day, but not going to burn anything. A sauna is usually 180 degrees by comparison. water boils at 212.

[RobWNY]

I think since there's so much different information being provided that doing as I posted earlier, checking each morning of our trip and adjusting accordingly, would be the best thing to do. I have a TPMS system so I'll know if pressures and/or temperatures get out of the normal range.

[CapriRacer]

Gonzo42 wrote:
As a rule of thumb, air pressure in tires incraase about one psi for a temperature increase of 10 degrees F. …...

Sorry that only applies to passenger car tires - 30 psi or so.

For higher pressure tires use 3% for every 10°F. So for an 80 psi tire, that's 2.4 psi for every 10°F - or from 45°F to 80°F, it's 8.4 psi increase.

[JimK-NY]

ajriding wrote:
......

My 80 pis tire went to 125psi just going from 80 degrees to 115 degree climate. This was combo of ambient temps and the heat generated from driving - mostly heat from driving with a lot of weight on the tires.

It is smart to check psi in this situation, but a warm tire would not need to be deflated back to the cold psi rating (in this case 80), rather something around 100 would be fine. .....

Absolutely, not fine and very dangerous advice. Never, ever deflate a hot tire because the pressure increases due to driving. If it is hot and you are carrying a heavy load at high speed, the solution is to slow down. Even then expect high pressure during highway driving in hot weather.

[Gonzo42]

I agree with the previous posts. Just wanted to mention that wear on the tire will indicate if your pressure and your driving is causing uneven wear you should re-asses. If your pressure is low, the wear will be close to the sidewall. If your pressure is too high, the middle of the tire will wear more.

[Beverley_Ken]

As you are going to do, check every morning, but I would bleed any off if it were only 5 psi or so. If it gets above 10 over yes. I may affect your handling and ride, (assuming a MH or tow vehicle).
Years ago, we left home (north of Toronto) , the temp was about -20F and pressures set for ambient cold at 80 psi and 65psi in front (c-class). Later in the trip, after getting on the road in the morning, the handling was a nightmare and horribly rough ride, only thoughts were about the pothole I'd hit the day before, not tire pressures. Next day I checked the tire pressure before getting on the road, The fronts were well over 90psi. After reducing the pressure to the appropriate pressures, the ride and handling were back to normal.

Ken

[time2roll]

Going 80F to 115F is fairly common for some of us in coastal CA driving to Vegas. And I will assure the OP no one is adjusting air pressure enroute.

[Grit_dog]

"My 80 pis tire went to 125psi just going from 80 degrees to 115 degree climate. This was combo of ambient temps and the heat generated from driving - mostly heat from driving with a lot of weight on the tires."

If this is actually true and not a typo, then you would have 3rd degree burns on your hands from touching the tire and the air inside would be roughly the temperature of a pizza oven.