Both cars have tire monitoring and also tell me tire temp. Run reset in fall and late spring/summer and see where the pressures settle after driving for a while and adjust accordingly. Along with tire rotation, keeps my tire wear even and ride secure, comfortable and safe. With Summer and Winter tires now showing the need to replace, wondering if I also need to buy new tire pressure sensors when replacing. Not easy to break the seal to retrofit once installed so would prefer NOT to have to mess with after a year or two of the new installs. How long can I expect tire pressure sensor batteries to last, given they are in sleep mode for approx. half of the year.
Hot tire pressure
- Thread starter Patman
- Start date
I just target 29 - 32 after a couple or three miles of driving. I find they spin up a bit too easily with more air in inclement Winter weather.True. I do realize that it’s complicated for a manufacturer to give a hot pressure because there are more variables. But I also think that it might be a good idea if owner’s manuals would mention that it’s a good idea to run 2-3 more psi in sub freezing weather. At the same time, I wonder what percentage of owners ever even check their tire pressure on a regular basis. Most pressures probably only get checked when they go to a quick lube place for an oil change (and even then I bet half of those places don’t do it either)
When I did my OC a month ago I set cold pressure a couple PSI over door placard since I was anticpating a 30 degree cooldown. Then a few day we had a warmup and I was banging around with 37 psi in the tires - that was hard on the suspension and steering was too fast and twitchy. 20F degree days are coming for us next week. Boo.
YMMV with supercars on the interstate or heavily-laden vehicles. Got to air-up the tires for the load carried - or high speeds anticipated
I just have a little tin can around town buzz bomb these days with good AWD. It's not too critical.
Patman
Staff member
My Corvette also has tire temperature as one of it's displays although it doesn't give an exact number, it just says COLD, COOL, NORMAL, WARM or HOT. I've actually never seen it say warm or hot. Most of the time it just sits at normal, although today I drove it for about an hour in 40 degree weather and it only moved from cool to normal at the end of my drive.
No, it's not!!
ALL gases - including nitrogen and air - behave the same in the range of temperatures and pressures commonly encountered by humans. The principle is called the Ideal Gas Law: PV = nRT.
Nitrogen is more temperature stable
Nitrogen is more temperature stable than air12. It forms about 78% of Earth's atmosphere and is the most abundant chemical species in air3. However, the atmosphere of Mars is only 2.6% nitrogen4. Liquid nitrogen, which is very cold, boils into nitrogen gas at room temperature and pressure5.
https://chemistry.stackexchange.com...ctuate-to-much-a-lower-degree-than-air-with-c
https://flowracers.com/blog/nascar-nitrogen-tires/
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Well that’s a load of crap.
From BMW
Wikipedia: Ideal Gas Law: Many gases such as nitrogen, oxygen, hydrogen, noble gases, some heavier gases like carbon dioxide and mixtures such as air, can be treated as ideal gases within reasonable tolerances [2] over a considerable parameter range around standard temperature and pressure.
Barry's Tire Tech: Nitrogen Inflation ALL gases are subject to what is called the Ideal Gas Law.
Barry's Tire Tech: Nitrogen Inflation ALL gases are subject to what is called the Ideal Gas Law.
More at permeation. There is a benfit to using a dry gas with lower permeabilty. Many outdoor coin op air pumps do not have adequate driers/separators, and you are introducing possibly as much as an ounce of moisture when you fill a tire in such a manner.
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That Barry's page was a great read, thank you for hosting/maintaining that site--it's a great knowledge resource!
Can I suggest an addition at the end of the page, where you're speaking to the possible cons of water in the tire? It's kind of a perfect storm scenario, but if you deflate a tire with extremely damp/liquid-water-containing air (like adjusting a tire that's overinflated), there is a risk of the tire stem valve getting iced and sticking open (causing a leak) or frozen closed (causing difficulty adding more air, if needed). I've experienced this exactly once in 28+ years of auto maintenance and driving, and recently read someone on here talking about the same (@ARCOgraphite, was that you im remembering?)(I'd thought it was unique to me!). The phenomenon earned me a free 'alteady-running-late' flat tire the next morning! Good times.
Haha
Patman
Staff member
That’s why I only fill my tires at Costco now. I wouldn’t pay for nitrogen, but when it’s free why not? I feel like just having a cleaner fill with no moisture in it is the biggest benefit of those nitrogen stations.
On top of rust around the beads on steel wheels, we can only imagine the bad effects of moisture on certain tire pressure sensors.That Barry's page was a great read, thank you for hosting/maintaining that site--it's a great knowledge resource!
Can I suggest an addition at the end of the page, where you're speaking to the possible cons of water in the tire? It's kind of a perfect storm scenario, but if you deflate a tire with extremely damp/liquid-water-containing air (like adjusting a tire that's overinflated), there is a risk of the tire stem valve getting iced and sticking open (causing a leak) or frozen closed (causing difficulty adding more air, if needed). I've experienced this exactly once in 28+ years of auto maintenance and driving, and recently read someone on here talking about the same (@ARCOgraphite, was that you im remembering?)(I'd thought it was unique to me!). The phenomenon earned me a free 'alteady-running-late' flat tire the next morning! Good times.
I just recall being amazed at the water spray and then trying bleed off some if that water from those coin-op tire pumps - all decades ago - before I jammed the air chuck on the Schrader valve stem and started adding air.
I think there were still pay phone kiosks around back then - but they were now them fancy "dial tone first phone" where you could get an operator to "reverse the charges" when you were short on change. Lol.
JHZR2
Staff member
Cold means cold. So it doesn’t matter if it’s 25C or -25C, that’s what they should have for load.
Some cars give at least an additional value to consider related to speed or loading.
I like the idea of hot pressure to be informed, but it is a variable related to tire air volume, ambient conditions, loading, speed, etc. Compensation seems prudent. I usually set cold pressures a few psi above the door card, and watch the cold pressures when things go down low.
Some cars give at least an additional value to consider related to speed or loading.
I like the idea of hot pressure to be informed, but it is a variable related to tire air volume, ambient conditions, loading, speed, etc. Compensation seems prudent. I usually set cold pressures a few psi above the door card, and watch the cold pressures when things go down low.
4WD
$50 site donor 2025
The flip side is it’s less safe in storage bcs it can displace oxygen if a cylinder leaks - almost got a guy who stored it in an area they did paperwork in often …
Regarding ambient air vs nitrogen fill: I believe the correct answer was posted above in post #29.
Simply put, pure nitrogen gas molecules are larger than the air mixture molecules that we breathe which is what all air compressors provide. The larger nitrogen molecules can't escape through the rubber compound of the tires as easily, therefore nitrogen-filled tires will retain their fill and pressures better and longer than tires filled with regular ambient air.
Having said that, I like to keep my tire pressures at 36psi cold all around. On the truck, if I'm towing or hauling a full load I'll bump it 1-2psi temporarily. I find that tire wear is consistent and even, especially when combined with regular re-balancing and rotation.
Simply put, pure nitrogen gas molecules are larger than the air mixture molecules that we breathe which is what all air compressors provide. The larger nitrogen molecules can't escape through the rubber compound of the tires as easily, therefore nitrogen-filled tires will retain their fill and pressures better and longer than tires filled with regular ambient air.
Having said that, I like to keep my tire pressures at 36psi cold all around. On the truck, if I'm towing or hauling a full load I'll bump it 1-2psi temporarily. I find that tire wear is consistent and even, especially when combined with regular re-balancing and rotation.
Mine will say warm and hot, but the PSI gives more indication of what's actually going on. I'll get them about 3-4 psi from cold before really leaning on the tire.
Nitrogen is not more stable than air. Air is 78% nitrogen, so the statement itself is ridiculous even if you don’t understand chemistry.
What’s ironic is that the article in your first link ended up refuting what you say. Here is the summary of the answer from your first link. It’s at the end of the article.
“Basically, pressure of nitrogen gas do not fluctuate less with change of temperature compared to normal air.”
So, you quoted an article, which disagrees with your point. That article happens to be truthful. The other piece of click bait garbage, well, is just Clickbait garbage.
People who understand chemistry, understand the universal gas law. PV
NRT. Oxygen, and nitrogen, both follow that.
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On that, we agree.
That said, I drain my compressor frequently, and have an in-line dryer with desiccant. I only use dry air to fill my tires, and my shop is far closer than the nearest Costco.
The reason dry nitrogen is used in aircraft tires has more to do with the dryness than the nitrogen.
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