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Author: Subject: Nitrogen inflated tires !
jack-sparrow
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[*] posted on 24-8-2006 at 07:07
Nitrogen inflated tires !


Here is a funny article from CBC news in canada :

source : http://www.cbc.ca/story/news/national/2006/08/22/nitro-tires...

Quote:

Nitrogen-filled tires appeal to Winnipeg drivers
Last Updated Tue, 22 Aug 2006 12:18:50 EDT
CBC News

A growing number of Winnipeg drivers who used to inflate their tires with regular air are now paying up to $8 apiece to fill them with nitrogen instead.

Unlike oxygen molecules, which are so small they leak through tires over time, nitrogen molecules are much larger, so the tires will stay fully inflated three to four times longer.

The result is a better drive, increased gas mileage and longer tire life for motorists who make the switch.

"Because the oxygen is no longer leaking through the walls, that tire isn't aging as it used to," said Jose Ferreira, who manages a Fountain Tire location that started offering nitrogen for tires last week.

Fully inflated tires also give cars better handling, making them safer to drive. CAA Manitoba spokeswoman Jeanie Dalman said they can also save drivers money on gasoline.

"If your tire pressure decreases by 15 PSI from the recommended tire pressure, that's going to increase fuel consumption by two per cent," Dalman said.

Nitrogen has long been used to inflate tires for jet airplanes and race cars. One convert to its use for street vehicles is Johann Leitgeb, who said he saw the practice on television.

"They showed a film about these heavy trucks, what they use in the oil sands, and they mentioned they are inflated with nitrogen," he said.


What a hoax

nitrogen molecule is 0.31 nm and oxygen molecule is 0.29 nm. Where is the big difference ? Race cars and jet planes are not suitable for a comparison with my hyundai crap.




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turd
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[*] posted on 24-8-2006 at 10:46


Quote:
nitrogen molecule is 0.31 nm and oxygen molecule is 0.29 nm. Where is the big difference ? Race cars and jet planes are not suitable for a comparison with my hyundai crap.

The difference between N2 and O2 is not so much about size, as it is about polarity. I vaguely remember something about membranes which would let one of the two pass more easily. Of course, considering that air is 70% N2, it does sound like a hoax indeed.
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[*] posted on 24-8-2006 at 11:18


I remember my chem teacher called the place that did this but I forgot what the answer was. She was wondering beccause of Grahm's law, and nitrogen is lighter than oxygen.

I guess the small size difference makes it last a LITTLE longer, and you know people these days will do anything to save a little.

[Edited on 8/24/2006 by guy]




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YT2095
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[*] posted on 24-8-2006 at 23:31


IIRC the reason is something to do with expansion / contraction over temperature ranges, apparently that`s why it`s use in aircraft tires, they can go from -40c at high alt and then up to 200+ upon touchdown, it doesn`t support combustion either.



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[*] posted on 25-8-2006 at 02:08


Could oxidation of the inside of the tyre be a problem when the usual 21% oxygen is present? Maybe it makes the rubber crack which enhances seepage of the gas inside.



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unionised
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[*] posted on 25-8-2006 at 05:10


"IIRC the reason is something to do with expansion / contraction over temperature ranges, apparently that`s why it`s use in aircraft tires"
All gases expand by practicallly the same extent on heating.
I seem to remember having heard that big tyres on planes are filled with He to save weight.
The only benefit I can see to using N2 rather than air is that it's less reactive. There is also the fact that N2 will be dry whereas air might not be.
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jimmyboy
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[*] posted on 25-8-2006 at 05:40


thats ridiculous - someone is making money at dumb people's expense.. heh
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[*] posted on 25-8-2006 at 07:26


@unionised,

The space shuttle tires are filled with nitrogen (as are most aircraft tires) due to its stability at different altitudes and temperatures. Due to the extremely heavy loads these bias ply tires are inflated to 340 psi (main gear) and 300 psi (nose gear).
taken from: http://www.airmichelin.com/space.html

I guess these guys know what they`re on about if the Space Shuttle uses it too.




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Chris The Great
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[*] posted on 27-8-2006 at 21:29


Well, sure, it might be worth it for your space shuttle, but methinks a Toyota's tires will not be experiencing the same kind of conditions the space shuttle does as it descends from orbit and then hits the ground at 200mph!

Still, if I had a gas station, I'd take advantage of the stupids for some extra $$$.
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[*] posted on 5-9-2006 at 12:47


Quote:
Originally posted by jimmyboy
thats ridiculous - someone is making money at dumb people's expense.. heh

i agree
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[*] posted on 5-9-2006 at 15:38


The only thing I can see filling tires with nitrogen would do (assuming normal driving temperatues, not outer space or something) would be possibly to cause the tires to last longer due to the rubber not oxidizing as quickly. But as far as performance, I really don't see how it would matter.

I remember once reading (in some sort of revenge article, of questionable validity) that if you filled someone's tires with pure oxygen they would eventually catch fire and blow out when the car was driven. Whether that would actually happen under any reasonable driving conditions is highly doubtful, but at least the theory would seem to make more sense than the theory of why tires should be inflated with nitrogen.

Hodges
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[*] posted on 6-9-2006 at 05:55


To me it also looks like bullshit, especially with the idiotic official explanation. I agree with Hodges about the reduced oxidation, but perhaps the consumers wouldn’t buy such an explanation as easily as the one about not needing to inflate the tires anymore.

However, I was wandering what influence would the osmotic effect have? I assume osmosis in gasses doesn’t nearly give as high pressures as in liquids, but could there be a measurable effect? (putting the naivety of the consumers aside, for a moment)
Diffusion is driven by the pressure difference and is thus oriented from the inside to the outside of the tire. Osmotic diffusion is driven by the difference in O2 concentration from the higher concentration to the lower and is thus oriented from the outside to the inside of the tire. The gas diffusion currents are thus counteracting. Of what significance could such an effect be?

I have forgotten how the osmotic pressure is calculated, but I remember it is based on the ideal gas equation. I would assume in gases it simply amounts to the difference in partial pressures, thus it would amount to 0.2 atm at the initial partial pressure of 0 atm for O2 in the tire. Assuming the speed of diffusion of O2 does not differ much from that of N2, this not be a very important factor considering the pressure difference is of about 1.2-1.5 atm in normal car tires (at least 6 times more). However, if the speed of diffusion between O2 and N2 differ a bit more it could become important, or no?

[Edited on 6-9-2006 by Nicodem]
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jack-sparrow
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[*] posted on 6-9-2006 at 07:06


I dont think it is an oxidation issue. Partial pressure of oxygen in air is 0.2 atm. Assume a tire contains 10 liters. At 30 PSI, you should have about 30 liters. Divide by 5 (O2 is 20% of air). 6 liters of oxygen. Divided by 25 l/mol at 300K. So you have 240 mmol of oxygen. You will not oxidize a lot of things with such a small amount.



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[*] posted on 6-9-2006 at 13:13


Besides that, there will be little loss of pressure (a fifth, not insignificant), but then, most of the pressure gained back as CO and CO2, assuming full oxidation (and not, say, crosslinking and such types of oxidation).

Tim




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S.C. Wack
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[*] posted on 6-9-2006 at 15:00


Local tire dealers have been doing this for some time.

I would hesitate to call bullshit (or pay $8 CAN) without direct comparison. We are talking about tens of thousands of miles, likely over several years, not the difference between night and day.

The devices are interesting.
http://www.purigen98.com/index.php?page=sysinformation
http://www.irtools.com/IS/product.asp-en-4635

Real comparisons are probably few for free.
http://www.tirelast.com/id5.html
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[*] posted on 6-9-2006 at 17:22


I'll happily call 'bullshit'. I do 600km a week in my car, I check the tire pressure about once every 6 months and its usually only down by a couple of psi - if that! My tires get replaced because the tread is gone - not through deteriorating rubber - and that takes 2-3 years.

Its like the bottled water phenomenon - who would have ever thought you could sell a bottle of water at twice the price of a bottle of Coke :o




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[*] posted on 6-9-2006 at 17:29


I'm still not convinced. This so-called "research paper" excerpt looks like BS to me. No competent researcher would write things like “about 125 of these tires wore out” or compose complete sentences in all caps, bold with an exclamation point at the end.

Their explanation for inside out tire rot has already been debunked here as a simple matter of math.

Without materials and methods outlined the numbers are <b>totally</b> worthless.

This whole thing is reading high on my BS-o-meter.

One more thing I forgot to mention: the "research paper" this is excerted from doesn't seem to exist at all. A google substring search yeilds nothing.

[Edited on 7-9-2006 by neutrino]




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[*] posted on 7-9-2006 at 13:41


Quote:
Originally posted by Twospoons
Its like the bottled water phenomenon - who would have ever thought you could sell a bottle of water at twice the price of a bottle of Coke :o


And bottled water is more expensive than gasoline I might add (at least around here). Of course, I recently noticed a store display for a particular brand of bottled water. It said "No other bottled water brand hydrates faster!" Yeah, I guess they can't be accused of false advertising for that one....

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[*] posted on 7-9-2006 at 16:09


The fact that you are unaware of studies does not mean that they don't exist, it means that they are hidden to those outside rubber.org, rubbernews.com, and elsewhere "in the loop". What they say is anyone's guess.
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[*] posted on 7-9-2006 at 23:57


i heard a story from a friend about bottled water BS

they were claiming cyclic water molecule stucture ie ice crystals dissolved in water!
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[*] posted on 8-9-2006 at 14:43


this is a total crock - i can't believe it even merits a second thought - our atmosphere is 80 percent Nitrogen - what is 20 more gonna do for a small tire - this may have an application for something larger but not a car...
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[*] posted on 8-9-2006 at 14:58


You're looking at it the wrong way. It's more like the atmosphere is 20% oxygen, what happens when you remove that?

But I agree, this looks like a crock.




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[*] posted on 8-9-2006 at 21:06


Or look at it like this: even though you remove the oxygen from inside the tire, its still 20% O2 outside the tire !



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[*] posted on 15-9-2006 at 08:59


Just a thought.
If the original hype admits oxygen leaks though the tyre walls at a significant rate, and oxygen causes the rubber to degrade, then filling the tyre up with pure nitrogen will cause a higher concentration of oxygen in the rubber tyre due to osmotic pressure.
mick
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[*] posted on 15-9-2006 at 09:25


Perhaps the increased tyre life-time is due more to people checking the pressure, making sure their tyres are not balding on the outsides or middle etc. and generally taking better care of them - as opposed to any physical benefit.



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