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 > Stupid question about tires

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d3500ram

Colorado

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Posted: 04/08/21 10:32am Link  |  Quote  |  Print  |  Notify Moderator

monkey44 wrote:

Crowe's 'stupid question' about nitrogen seems pretty smart, after all, don't it??


It is a really is good question especially if one wants to get in the weeds about it.

Could member JoshuaJim’s reply of regular air being “fully” replace with nitrogen be calculated by incorporating the basic theorem of calculus? I have no idea what the equation would be. But as X approaches infinity (if X= time) we could see just how close to 100% that N can become.

Would it in fact be in the vicinity of 1,000 years?

wanderingbob

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Posted: 04/08/21 10:35am Link  |  Quote  |  Print  |  Notify Moderator

Remember it would be impossible to " Purge " a standard wheel . The bead will " break " allowing everything out ! So when ya let all the air out the tire is still complexly full of air that you then place nitrogen on top off !

Dutch_12078

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Posted: 04/08/21 10:51am Link  |  Quote  |  Print  |  Notify Moderator

Purging the air in the tires by deflating them and then reinflating with nitrogen a couple of times, it's possible to reach a ~98% nitrogen fill. Even just deflating the tire and refilling with nitrogen once can reach a 95% fill since the remaining 78/20/2% air is compressed to a smaller volume when the tire is pressurized. Is it worth the trouble for most common personal vehicle use? No...

* This post was edited 04/08/21 10:58am by Dutch_12078 *


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Lwiddis

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Posted: 04/08/21 11:05am Link  |  Quote  |  Print  |  Notify Moderator

"With nitrogen tires, you get the really, really cool green valve caps!"

I find green valve caps REALLY impress the ladies!


Winnebago 2101DS TT & 2020 Chevy Silverado 1500 LTZ Z71, 300 watt solar-Lossigy 200 AMP Lithium battery. TALL flag pole. Prefer boondocking, USFS, COE, BLM, NPS, TVA, state camps. Bicyclist 14 yr. Army -11B40 then 11A - (MOS 1542 & 1560) IOBC & IOAC grad


Crowe

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Posted: 04/08/21 11:33am Link  |  Quote  |  Print  |  Notify Moderator

My faith in myself is restored by all of your answers-thanks! It's also a very interesting discussion.


I may not have gone where I intended to go, but I think I have ended up where I needed to be Douglas Adams

RV-less for now but our spirits are still on the open road.

CapriRacer

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Posted: 04/09/21 05:05am Link  |  Quote  |  Print  |  Notify Moderator

DrewE wrote:

..... The only component of air that expands or contracts significantly differently than nitrogen alone is water vapor. .......


Sorry, that is not true.

Water vapor behaves like an ideal gas EXCEPT near the dew point. Even a tire with liquid water in it will eventually lose all that water through the sidewalls, and become like the outside air - which is normally NOT near the dew point.


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Thermoguy

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Posted: 04/09/21 01:42pm Link  |  Quote  |  Print  |  Notify Moderator

OK - so a point of view from the other side. I have had 3 sets of tires on the same vehicle, same basic tire as well, some changes over the years, but same tire. First set, new with vehicle, a friend recommended nitrogen due to the low profile tires. A nearby place removed the air and replaced with nitrogen, their pump system did something that seemed like it was removing and refilling in a step process, but assuming you can't get all the air out. So, my experience, the tires held up great, 80K miles, stayed within a few pounds regardless of hot and cold weather. Next set, different tire shop (discount) regular air. Tires only lasted 40K miles, had issues with one that kept losing air on a regular basis, no one from 3 different shops could find anything wrong with the tire, but I had to fill regularly. Now, 3rd set, same brand, but this time Costco. Costco uses nitrogen. Tires have been on for over a year, haven't had a single tire issue, tire pressure stays within a couple pounds. So, yes, I think nitrogen is a good thing, but also don't search it out and have never paid extra for it. But, there are shops that have nitrogen compressors, like Costco.

Just my 2 cents from experience, fact not fiction.

Jarlaxle

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Posted: 04/11/21 10:58am Link  |  Quote  |  Print  |  Notify Moderator

Total scam, a way to separate the gullible from their money.


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Jarlaxle

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Posted: 04/11/21 11:00am Link  |  Quote  |  Print  |  Notify Moderator

fj12ryder wrote:

ktmrfs wrote:

PartyOf Five wrote:

Our mechanic suggested nitrogen in the car tires if we did a rotation as winter approached. Apparentky it doesn't contract and expand as much in the cold and so is better in extreme temps.
That was already a few years ago- the fad seems to have died down.


NOT true. all gases follow boyles law PV=RT. since V (volume) is constant, P is strictly a function of T (temperature) where T is absolute temp, E.G. room temp is 273 or so Kelvin

Nitrogen molecules are slightly larger than Oxygen, so pressure drop from migration through the tire will be very slightly less.
Personally I think the less change in pressure is caused by the dryer nitrogen compared to regular air. There should be no water vapor in the nitrogen fill, and water vapor will expand and contract more than gases without the water vapor. JMO anyway.

But basically unnecessary, just a way for some place to make a few extra pence.


If you're worried, a water separator for your compressor is about thirty bucks.

DrewE

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Posted: 04/11/21 12:37pm Link  |  Quote  |  Print  |  Notify Moderator

CapriRacer wrote:

DrewE wrote:

..... The only component of air that expands or contracts significantly differently than nitrogen alone is water vapor. .......


Sorry, that is not true.

Water vapor behaves like an ideal gas EXCEPT near the dew point. Even a tire with liquid water in it will eventually lose all that water through the sidewalls, and become like the outside air - which is normally NOT near the dew point.


Water vapor not near the dew point does indeed act as an ideal gas, for practical purposes.

Air from a compressor (at least in somewhat humid climates), if there is no dryer in the line, will be saturated and pretty close to the dew point at the tank pressure, as evidenced by the condensation that collects in the compressor tank. Tire pressure is lower than the tank pressure, which lowers the pressure dew point in the tire somewhat, but it's still well in the range of ambient conditions that a tire is likely to be exposed to.

While rubber is somewhat more permeable to water than to air, it's still a very slow process for it to get out. (It's still more permeable to carbon dioxide, and it takes a long time for a tire filled with that to deflate noticeably.)





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