nitrogen tyre inflation

[Guest callithrix]

Just came upon this while checking up on the Pirelli Strada. It's suppose to increase tyre life by up to 25% and reduce rim oxidation. http://www.mtdealer.com/t_inside.cfm?actio...et&storyID=1207

[jrt]

LOLOLOLOLOouch.... fell off the chair there.

 

Sorry, this is a load of horseshit.

Let's take a look at it:

It has more mass, so it migrates through the tire three to four times slower. The result: Tires hold their psi longer.

Mass has nothing to do with a tire loosing it's inflation. It's based on the size of the molecules and the permeability through the rubber. In fact, the molecular mass of N2 is less than O2 and CO2, the principle components of 'air'. There's some water in their as well- depends on where you live. But the fact is that the effective mass of the elements changes even more slowly than the molecular mass and you're looking at a 6% _increase_ in mass from N2 to O2. I thought everyone wanted _lighter_ wheels anyway (btw, using only nitrogen would lighten your wheel assembly by about 2-4 grams).

It runs about 20% cooler. Less heat results in less tire degradation.

Cough-bullshit-cough-cough. The heat capacity of common diatomic gasses are all about the same. Heat capacity is determined by the molecular degrees of freedom (how the individual molecules can stretch, bend, or move). All diatomics can do is stretch N=N ..... N = N then back to N=N. Triatomics have more exotic bending modes. So...the heat capacity of the diatomics is generally less than triatomics, because they have fewer modes to adopt. It's outlined in the equipartition theorem- you can read it here.

It drastically reduces oxidation on the rim and inner-liner (nitrogen systems almost totally eliminate oxygen -- the cause of oxidation -- from the mix).

Oxygen isn't the culprit here...well not entirely. O2 already makes up about 20% of the atmosphere. If oxygen was that reactive to the rims, then why dont the OUTSIDE of rims rust away? Because there's a protective oxidation layer already on any exposed aluminum or magnesium. Essentially, in the first millisecond of exposure to air, any aluminum or magnesium oxidises (same as anodizing). The oxidation layer is impermeable to further oxygen...no more oxidation. It's called passivation and its the reason that the Statue of Liberty hasn't rusted away as well (it's copper of course). The best thing you can do is put DRY air in your tires. Water is far worse, because it carries ions around which conduct electricity. O2 can act as an oxidant, water carries the charge, and voila- you can turn a perfectly good rim into a battery with the rim serving as the sacrificial reductant (it turns to rust )

It is environmentally safe.

And air is dangerous? I better go get the duct tape and plastic bags, I guess.

 

There's an expression I've read for this sort of thing:

Snake oil is exactly that- Rendered snake.

[DeBenGuzzi]

I'm glad someone gave me the 411 on this because I had seen it b4 and pondered doing it if I came across a place that had it. But NOT now. waste of money. Thanks for the heads up. They're just trying to steal from the ignorant and the uninformed. Why don't we just get Magnesium rims and fill the tires with helium? hydrogen? that could redice some weight OR, OR how about michelins new Tweel? screw inflation or flats.

[big J]

I dont know about all the science stuff,but I know H**da use nitrogen filled tyres at the T.T. Why do this if there are no benefits in using the stuff?

[DeBenGuzzi]

Maybe there are no negatives either and they're just trying it out. to be different you know honda

 

[Guest callithrix]

So how do you really feel about using nitrogen in your tyres, JRT?

[jrt]

I'm all for using nitrogen in tires (tyres). In fact, I use 78% nitrogen every time I fill up my tires.

 

Now, to be truthful, there may be certain advantages to using purified gasses, but they are pretty limited. Hydrogen? I'm not so sure about it. It's light, but it's a tiny molecule, and tends to escape quickly (ever had a hydrogen balloon? they last 4 hours max, then the hydrogen leaks out of the balloon). Maybe Honda has a good tight polymer for their tires. H2 is also flammable, but I doubt this is a problem except in a crash.

The advantage I see to purified nitrogen is that it's dry. Compressed air always has a bit of water in it, and that's not good for rims, I'll grant.

So....do it if ya' want. The prices looked cheap enough for a one-time experiment, but a bit high for me to do it on a long term basis. Hmmm, I do have a tank of nitrogen in my laboratory. I have a tank of argon as well, but I think that would just slow me down

 

 

BTW, never, never, never breath in argon like you do helium. Helium is very light, and passing through your vocal cords, it makes you sound like mickey mouse. Argon is dense, and is supposed to make you have a deep voice. Trouble is, our lungs are like vases, and its really hard to push dense gas out. Sooo, it's really easy to pass out from lack of air.

[pete roper]

I was going to make some silly comment about always using a mix of about 70% Nitrogen, 20% Oxygen, 2% Carbon di-oxide and a *secret* formula of other trace gasses but Jason beat me to it!!!!

 

Some bicycle racers use Helium in their tyres forweight savings and I suppose that if you looked like this and/or worked for Honda you might think that the savings in unsprung weight might be worth worrying about but hey! We're talking about a Moto Guzzi here, it weight about half as much as a house, no, make that a small palace! Savng weight by filling the tyres with Helium would be about as effective as trying to empty the Pacific ocean by carrying it across the Panama isthmus one teaspoon at a time and emptying it into the Carribean!

 

I love these stupid ideas, they're like those geniuses who periodically con the press into believing they've built an internal combustion engine that runs on water or some sort of perpetual motion machine powered by thought waves! Brilliant! I wish I was that imaginative. My secret trick is that I find that my bike goes ten times faster if I ride it wearing a wet-suit full of custard and enclose my head in a goldfish bowl full of warm beer, hang on, that sounds just like riding in England in winter!

 

Pete

[Guest bshpilot]

one of the REAL advantages of 100% nitrogen filled tires

is that they are not affected by temp. (doesnt expand or

contract) as much.

 

also no moisture...

 

hell even COSTCO is filling tires w/ it (for FREE).

 

aircraft use it in their tires too.

[jrt]

Well, according to the ideal gas law, PV=nRT, all gasses have the same expansion/temperature at low pressures. I'll have to look up the pressures at which they start to deviate from ideality, but I suspect it's several hundred psi.

J

 

PV=nRT

P=pressure

V=volume

n=number of moles of gas

R=gas constant

T=temperature

 

[edited- revised my estimation based on the post below- edge makes sense]

[edge]

I concur that nitrogen is a better solution for high presure systems; tires, struts, accumulators, etc.. It has been the gold standard in aviation for decades.

 

As far as cost benifit in motorcycle tires... <_ if you have easy access to a quality source and proper check fill units comes in high pressure tanks sure it the best... for stability being totally inert. as far good ol air our systems.. lets just say is at least best tied with extra overhead required pure nitrogen i don see bang buck especially since we operate most part stock alloy rims low tires.... src="%7B___base_url___%7D/uploads/emoticons/default_knownothing.gif" alt=":huh2:">

[Guest aironepony]

When I was in Mandello last year I noticed that the Factory Shop was selling canisters of Mandello Del Lario air for tyre inflation.

 

The air is compressed on the shores of Lake Como and has a trace of garlic added to it to ensure sidewall flexibilty at all temperatures.

 

This is a little known secret of Guzzi's racing sucesses in the past.

[Guest Nogbad]

jrt is right, I can't see any advantage to nitrogen over dry air either.

[Guest jasper]

this is such a funny story.... selling air!!

 

IF the claim is right: no or very little N is leaking through the tire...

so when the tire looses pressure it basically leaks out everything but the N.....

so in the end you have filled your tires completely with N.... don't now after what time that is but i am pretty sure it would be noticable that after a while our tires wouldn't deflate as much which just isn't the case..

 

as an expermint i inflaten 2 of my cartires with the stuff and guess what..... no diference...

 

So it might be just a quicker way to get a better N ration in the tyres but that's a lott of money.. (i am a poor bastard and like to econmise on things like air....)

 

 

Ciao

 

jasper

[k7qz]

this is such a funny story.... selling air!!

 

Why not? In this country alone they sell billions of dollars of bottled water each year when the same stuff comes out of your kitchen faucet for free.

 

Go figure.....

 

-Mike