Sciencemadness Discussion Board

Nitrogen inflated tires !

jack-sparrow - 24-8-2006 at 07:07

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.

turd - 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.

guy - 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]

YT2095 - 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.

Nerro - 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.

unionised - 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.

jimmyboy - 25-8-2006 at 05:40

thats ridiculous - someone is making money at dumb people's expense.. heh

YT2095 - 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.

Chris The Great - 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 $$$.

jellysplat - 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

hodges - 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

Nicodem - 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]

jack-sparrow - 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.

12AX7 - 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

S.C. Wack - 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

Twospoons - 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

neutrino - 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]

hodges - 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....

Hodges

S.C. Wack - 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.

tumadre - 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!

jimmyboy - 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...

neutrino - 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.

Twospoons - 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 !

mick - 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

Ramiel - 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.

tumadre - 15-9-2006 at 20:39

have we cured the ultraviolet light problem? or the normal wear issue? or do we have ozone reducing catylists impregnated in the tyre? I think not.

this is just BS

however, the argument that oxygen leaks through the tyre is valid, but prove that it is harmful to the rubber

S.C. Wack - 16-9-2006 at 01:11

You need more than anecdotal evidence on lack of oxygen leakage, you need actual side-by-side comparisons of cold tires periodically. I find it difficult to so easily call bullshit outright on this without applying anything resembling actual scientific method.

Remember that there is more claimed than seepage, there is also the claim that wear and tear is reduced by eliminating oxidation from the interior.

As for neutrino's doubts as to the competency of Sperberg, I can't say; but Sperberg has probably had more papers published in a journal (2) than anyone here. What he's done more closely resembles science than the research of others in this thread.

apidej - 16-9-2006 at 15:01

good

turd - 17-9-2006 at 02:58

Quote:
You need more than anecdotal evidence on lack of oxygen leakage, you need actual side-by-side comparisons of cold tires periodically.

No, it's the other way round: extraordinary claims demand extraordinary evidence. And "I've published it" doesn't count as evidence.

unionised - 17-9-2006 at 11:14

"Sperberg has probably had more papers published in a journal (2) than anyone here."
I doubt that.
Anyway, since there are 2 groups of people here; those who believe there may be something in this claim and those who don't. Yet there are, it seems, none who can be bothered to do the experiment, I don't see this thread progressing.

The observation that, whatever you do to the inside of the tyre, the air will still oxidise the outside is reasonable, but it presuposes that the rubber is the same on the outside as the inside; I don't think that's true.

My understanding is that people replace tyres because the treads wear out; so whatever happens inside is not going to improve the longevity of the product.

S.C. Wack - 17-9-2006 at 13:22

That is exactly the problem that I see here. I don't know about the effect on tires and really don't care. What I do know is that those who haven't done or at least examined experimental work seem unqualified for the job of pronouncing verdicts on subjects that they have no innate insight into. I would think that chemists would understand, thus my shock. It all seems more unscientific than the claims made; whether true or wishful interpretation of some published experimental data.

Ohm might understand my point.

If I was given to having an opinion without road testing, I would sooner form an opinion based on what large truck fleets are doing, as their tire costs are very high; rather than trying to apply some insight into tires that I don't have.

turd, I don't understand your post at all. How is the opposite of needing more than anecdotal evidence helpful in determination of wear? Anecdotal evidence trumps scientific method? WTF?

tumadre - 17-9-2006 at 22:44

I am NOT convinced that oxygen is in fact harming the tire

look on the inside of any old and cracked up tire, and you will find the inside to be fine.
and another good cause of wear is the steel on rubber interface internal to the tire.

at very high pressures and temps, the O2 might break down the steel-rubber interface (water would help that)

but for automobile applications? there are a lot of people filling tires with N2, I'm suprised auto makers don't recommend it.

turd - 18-9-2006 at 00:14

Quote:
turd, I don't understand your post at all. How is the opposite of needing more than anecdotal evidence helpful in determination of wear? Anecdotal evidence trumps scientific method? WTF?

My point was: the burden of proof is on the one claiming dubious things. And the more extraordinary the claim, the more extraordinary the evidence that is needed. So far I'm not convinced at all (not that I care about people wasting their money on N2-inflated tires, homeopathy or whatever).

unionised - 18-9-2006 at 11:11

Does anyone remember that the original website cited said this
"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"

That sort of claim needs a hell of a lot of evidence backing it before it begins to contradict many years of scientific knowledge.
I really think that, as a scientist ( A chemist as it happens) I really can call bullshit on that without needing to so much as look at a tyre.
Is there anyone out there who realy thinks oxygen is a lot smaller than nitrogen?
This isn't even bad anecdotal evidence as far as I can see; it's fraud and I think this page from another site cited speaks volumes
http://www.purigen98.com/index.php?page=research

You really can fool some of the people all of the time and some of them will pay for nitrogen filled tyres.
Even the report saying it's worthwhile is a bit understated.

"Nitrogen’s slower permeability characteristics coupled with its bone-dry nature may partially ameliorate some field abuse conditions, including long term inflation maintenance neglect, improper repairs and certain types of tire pressure monitor malfunctions. Even though high purity nitrogen is no guarantee of performance and will not undo the many forms of damage or abuse that can lead to tire failure, it offers a low cost, risk free and positive service opportunity that has finally become commercially and technically practical”.

Let's have alook what that says.
It MAY help defer the problems due to neglect.
The lack of water (which doesn't react much with rubber) is given as one of the advantages.
Nitrogen offers no guarantee of performance.

That's from the bloke paid by the manufacturer of the kit.

The "published" report includes the following
"When a tire lives to wear out, the oxygen slowly migrates and permeates its way into and through the tire cord body and finally into the under tread and then into the tread itself. It takes a long time for an appreciable amount of oxygen to reach the tread since most of the oxygen gets waylaid along the way by the liner, and then the cord arid cord insulation compound. "
Why in the name of God does he assume that oxidation is due to air coming from inside the tyre? What's wrong with the air outside it? Doesn't he realise that there isn't a lot of air in a tyre; but there's plenty of it out here?

Were those "reports" peer reviewed. Are they only published in the sense thet they are on the net?


BTW, "have we cured the ultraviolet light problem? or the normal wear issue? or do we have ozone reducing catylists impregnated in the tyre? I think not."
Er.. actually, yes; carbon black is used as a filler in tyres, it absorbs UV very well and it also catalyses the decomposition of ozone.


[Edited on 18-9-2006 by unionised]

S.C. Wack - 18-9-2006 at 12:48

You are allowed to search the internet, too. I mentioned on the first page where the available (to members) reports are. They are in rubber industry journals and the proceedings of ACS Rubber, just last week there were some related papers presented.

There is only one paper (in two versions) available to the public AFAIK, a study of internal oxidation that has little to do with the real world except in theory:
http://www.getnitrogen.org/pdf/print_articles/Ford%20Baldwin...

At least one (Sperberg, 1968) seems to attempt something of use or at least fakes it, but obviously what is needed is real passenger cars driving real miles, combined with cost/benefit analysis. No one seems interested in funding such a venture.

unionised - 18-9-2006 at 22:02

Have tyres changed since 1968?

mick - 20-9-2006 at 14:25

An easy experiment to do to check the porosity of rubber could be to inflate a balloon with air and see how long it lasts Inflate a ballon with nitrogen and see how long it lasts.
My personal experience is that 3 rubber balloons inserted inside each other and filled with argon or nitrogen, the outer balloon will disintergate due to oxidation.
mick

Twospoons - 20-9-2006 at 20:20

Quote:
Originally posted by unionised

"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"

That sort of claim needs a hell of a lot of evidence backing it before it begins to contradict many years of scientific knowledge.
I really think that, as a scientist ( A chemist as it happens) I really can call bullshit on that without needing to so much as look at a tyre.
Is there anyone out there who realy thinks oxygen is a lot smaller than nitrogen?


The difference in size may not be much, but the difference in diffusion rates can be considerable. This is how pressure swing adsorption air separators work. I was looking up physical properties of polyimide yesterday, and amongst the data I was after I noticed that the permeability for oxygen was over 3 times that of nitrogen ref . For the zeolites used in PSA separators the difference can be 10x, IIRC.
But while there is a potential basis in reality for using N2, $8 a fill is still rather steep - given the rather dubious benefits. What does a tyre cost over there, anyway? I can get a good tyre here for NZ$125.

unionised - 21-9-2006 at 11:48

We use nitrogen generators at work that rely on exactly that effect.
I was just pointing out that the site talked bull.

[Edited on 21-9-2006 by unionised]

richard - 30-9-2006 at 12:10

If the case is true that oxygen is lost, refilling your tyre will gradualy deplete the amount of oxygen any way. Bit silly paying $8 for some thing which would happen anyway.