Has anyone conducted such a test? I know my rig has air in the tires now, and I see ~16-18psi increase from cold to hot on the fronts, ~ 10-12psi on the drives and ~10 on the tags. I'm wondering if going to nitrogen would have less of a pressure increase and if so, any guesses as to how much?
Yes it does help but I've never worried about it. We use 100% nitrogen at work and I only use 78% at home. Good enough for me.
https://www.tirerack.com/tires/tiretech/techpage.jsp?gclid=Cj0KCQiAiJSeBhCCARIsAHnAzT-n150LEjM8zlc6TkB67Up88iLuJSsfnVTwohadME1T4K1ndBbvceoaAkYBEALw_wcB&techid=191&ef_id=Cj0KCQiAiJSeBhCCARIsAHnAzT-n150LEjM8zlc6TkB67Up88iLuJSsfnVTwohadME1T4K1ndBbvceoaAkYBEALw_wcB:G:s&s_kwcid=AL!3756!3!354820920608!e!!g!!air%20vs%20nitrogen&gclsrc=aw.ds
Quote;
Overall, inflating tires with nitrogen won't hurt them and may provide some minimal benefits.
Is it worth it? If you go someplace that provides free nitrogen with new tires, why not? Additionally we've seen some service providers offering reasonable prices of about $5 per tire (including periodic adjustments for the life of the tire) to a less reasonable $10 per tire (with additional costs for subsequent pressure adjustments) or more as part of a service contract, which we believe exceeds the value of nitrogen's benefit.
Rather than pay extra for nitrogen, most drivers would be better off buying an accurate tire pressure gauge and checking and adjusting their tire pressures regularly.
Maybe.
If you have DRY air, there is very little difference between it an Nitrogen. Both follow the Ideal Gas Law (PV=nRT).
If you have wet air/water in your tires (common from those convenience store coin operated pumps) there will be a greater difference as water vapor does NOT follow the Ideal Gas Law.
IMO, fill with dry air (like from your coach's on-board air system that has the air dryer and don't worry about it.
I used to fill my 5th wheel's tires with Nitrogen in the fall when we started headed south. It was nice always having the same pressure as we travelled through various climates and elevations in the high desert from Boise to Phoenix/Q. I ultimately decided it wasn't worth the hassle of finding it though and that's doubly true with the coach now.
Elliott,
Are you comparing Nitrogen with the (wet) air that comes out of compressors without an air dryer? If so, agree (physics) that there will be a less change in PSI for a given temperature change with Nitrogen.
But, with any "content" in the tires, just short of 200 years of physics says there WILL be a PSI change with temperature change.
http://www.google.com/search?q=+PV%2B+nRT&client=firefox-b-1-d&ei=C7fFY-i-JfKIwbkP3vC8iAM&ved=0ahUKEwio8LOi-sz8AhVyRDABHV44DzEQ4dUDCBA&uact=5&oq=+PV%2B+nRT&gs_lcp=Cgxnd3Mtd2l6LXNlcnAQAzIFCAAQkQIyBQgAEJECMgkIABAHEB4Q8QQyCQgAEAcQHhDxBDIJCAAQBxAeEPEEMgkIABAHEB4Q8QQyCQgAEAcQHhDxBDIJCAAQBxAeEPEEMgkIABAHEB4Q8QQyCQgAEAcQHhDxBDoKCAAQRxDWBBCwA0oECEEYAEoFCEASATFKBAhGGABQgQVYgQVghQ1oAXABeACAAesCiAHrApIBAzMtMZgBAKABAcgBCMABAQ&sclient=gws-wiz-serp
Yes, it was "wet" air, so the fluctuations were pretty noticeable that time of year going in and out of the eastern Sierras.
Elliott: Here is a combined formula for ideal gas law,
P= (PTV)/(TV)
Where;
P=Pressure
T=Temperature -- BUT for accurate results Temperature must be measured in Kelvins.
V=Volume
You read the formula Pressure equals Pressure times Temperature time Volume DIVIDED BY Temperature time Volume.
If you keep the volume the same size you can throw those terms away.
Use the same unit of measure for both pressure and volume.
Wanna do proportions?
The primary purpose of selling compressed nitrogen for tires, is to compress our wallets!
Keep in mind that tire inflation recommendations are "Cold" pressure. They allow for the pressure increases due to temperature. That increase doesn't happen with nitrogen.
Actually it does.
Defying the Ideal Gas Law is only something Nitrogen salesmen dream about and mislead with.
It all started because Cup cars filled their tires with nitrogen . Why? Cuz we used nitrogen bottles to run the air guns .
Then some science guy says that the molecule is larger and clean gas has less moisture in it and this it will build less pressure at the same temp. It dies build a pound less pressure .
It will leak slower. Not required for most situations imho
Unless one fills the tire when it's off the bead under a vacuum. Then filled with nitrogen. You are going to have 'some' air in it.
Just check and adjust pressure before a long drive and you should be good.
Or, one can whip out those slide rules and over analyze and adjust the pressure for that extra can of soup you put onboard and spike your blood pressure worrying too much about such things.
Always hated PV-nRT
Never know which n to use LOL
I was having the same thoughts as well as I get ready to purchase a new set of tires. My thought on this was. If I'm supposed to change tires every 5 years I see little if any advantage of going through the hassle of nitrogen filled tires. I carry a small tank now for the Jeep that came with nitrogen filled tires. Doesn't take up much space and last almost a year. Carrying something big enough to service the coach tires is out of the question for me. Maybe some truck stops would have it available but I doubt it would be free.
As far as the pressure increase. I would guess the engineers accounted for that. Class 8 trucks have been on the road a long time using truck stop air I'm guessing.
As Protech Racing has pointed out, this nitrogen gas nonsense began when people who need to service their equipment track side started carrying a bottle full of nitrogen gas pressurized at better than 2,000 PSI because it was easier than schlepping an air compressor and looking (fighting) for an electric outlet to power the compressor.
At this point I decided to fill just the front two tires with nitrogen. Previous trips have shown 15-16psi increase from cold to max (110-126). Unfortunately my Q trip was cancelled, but after my next trip I'll report if there is any significant difference in pressure rise with the nitrogen.
BTW, it took 1400psi from the bottle to fill each tire.