Nitrogen Filled Tyres

[d00dz]

I was taking to the tyre dude today as I was getting my T1R's fitted.

He mentioned that for performance cars its best to have nitrogen in the tyres instead of air.

So.. What are the pros and cons? He said @ $9 a fill for one tyre.

What happens if you break down or if you have a punture? What happens.

Does anyone use this stuff for road use? or mainly for track?

Ive search the word nitrogen and nothing comes up in relation to tyres (only one person has said they will do it.).

Any info would be good.

[Damo]

I was taking to the tyre dude today as I was getting my T1R's fitted.

He mentioned that for performance cars its best to have nitrogen in the tyres instead of air.

So.. What are the pros and cons? He said @ $9 a fill for one tyre.

What happens if you break down or if you have a punture? What happens.

Does anyone use this stuff for road use? or mainly for track?

Ive search the word nitrogen and nothing comes up in relation to tyres (only one person has said they will do it.).

Any info would be good.

<{POST_SNAPBACK}>

pros.

Nitrogen does not contain moisture and is much more tolerant of change in temp. eg less expansion or retraction therefore keeps a more stable pressure in hotter or colder conditions. Hence they use it in aircraft tyres.

cons.

its heaver than air, its expensive.

What happens if you break down or if u have a puncture?

Common sense tells me to either call for help or change the tyre.

At 9 bucks a tyre i would not waist your money. if u go to the track simply drop the pressure in your tyres. when they warm up they will increase pressure.

[siksII]

waste of money, how are u finding the t1-rs?

Edited October 28, 2005 by siksII

[scathing]

Unless you're going to use it for track work, or you've got your own nitrogen pump, I don't think its worth it.

The pros given by Damo are correct. You don't get the changes in tyre pressure that you do with air as the tyre heats up, which makes them more consistent and less likely to overheat.

But its hard to find a pump, and so if you get a slow leak or want to tune your tyre pressures you'll be out of luck.

When I get a second set of rims I'll probably use nitrogen in my track tyres, and use regular air in the street tyres.

As an aside, which tyre dude has been the only one to say they'll do it?

[scathing]

cons.

its heaver than air

Have you got any references for that?

Air is just under 80% nitrogen, and 20% ozygen. You've got 1% Argon, and everything else is just a rounding error.

Oxygen and argon are heavier than nitrogen, so assuming you're scientifically rigorous enough to be comparing the weight at the same temperature and pressure there's no way pure nitrogen could weigh more than air.

To the best of my knowledge you don't have to run higher pressures with pure nitrogen than air but I could be wrong. If so, then I guess nitrogen-filled tyres will weigh more...but you'd have to be a bloody good driver to notice.

[Damo]

Have you got any references for that?

Air is just under 80% nitrogen, and 20% ozygen. You've got 1% Argon, and everything else is just a rounding error.

Oxygen and argon are heavier than nitrogen, so assuming you're scientifically rigorous enough to be comparing the weight at the same temperature and pressure there's no way pure nitrogen could weigh more than air.

To the best of my knowledge you don't have to run higher pressures with pure nitrogen than air but I could be wrong. If so, then I guess nitrogen-filled tyres will weigh more...but you'd have to be a bloody good driver to notice.

<{POST_SNAPBACK}>

Yep your right, got it mixed up. Sorry, had 1 too many beers last night.

[Sydneykid]

Have you got any references for that?

Air is just under 80% nitrogen, and 20% ozygen. You've got 1% Argon, and everything else is just a rounding error.

Oxygen and argon are heavier than nitrogen, so assuming you're scientifically rigorous enough to be comparing the weight at the same temperature and pressure there's no way pure nitrogen could weigh more than air.

To the best of my knowledge you don't have to run higher pressures with pure nitrogen than air but I could be wrong. If so, then I guess nitrogen-filled tyres will weigh more...but you'd have to be a bloody good driver to notice.

<{POST_SNAPBACK}>

The 100% nitrogen filled tyres don't increase pressures as much as ambient air does when the tyres get hot. So they are more stable in their tyre pressures. My understanding is this is mostly due to the humidity (H2O) pressent in ambient air. Which, when it gets hot, breaks down into hydrogen and oxygen and increases the pressure accordingly.

So when they say "humidity is 40%", what does that mean to the 79.5/19.5/1 mixture? Does it become 47.5/11.5/1/40?

If so, that's why the pressure goes up so much if you have 40% of the contents of the tyre splittting into hydrogen and oxygen.

cheers

[MerlinTheHapyPig]

most of the benefits you get out of nitrogen filled tyres, can be achieved by using dry compressed air.

Moisture content in the gas you use plays a much larger part than the gas itself.

Aircraft tyres tend to use them because it's an inert gas, and reduces the risk of fires/tyre explosions.

[d00dz]

hmm interesting..

[Kinks]

waste of money, unless you're serious about your racing.

[cd04]

SK,

when they say that humidity is 40%, they are talking about 'relative humidity' (ie the moisture in the air as a percentage of the max moisture the air can hold)

Absolute humidity, which would be the moisture in the air, is much less (2-3% IIRC)

[scathing]

Which, when it gets hot, breaks down into hydrogen and oxygen and increases the pressure accordingly.

I'm not sure what the activation energy of water is, but are you sure that there's enough heat in the tyres to do that kind of thing? The last time I hit the track my tyres only reached around 50 degrees on the surface of the rubber.

And what do you do afterwards? Anyone who's studied the history of airships knows how safe hydrogen and oxygen are when mixed together and heat is applied. Also, since gases occupy more volume per molar count than liquids, that would leave your tyres with a higher "at rest" air pressure afterwards. Of course, depending on the humidity in the tyre in the first place it may or may not be detectable with a commercially available gauge.

If that was enough to break down hydrogen and oxygen, boiling water in a semi-sealed environment (like a kettle) where the boiling water vapour is kept at 100 degrees+ before being vented to the atmosphere would probably get you killed if you smoked anywhere near it.

Once again this is pure speculation on my part (I wouldn't even call it a hypothesis since I'm not that up on chemistry), but it just seems like if there was enough heat in tyres to break water down to its base elements there would be a lot more cases of tyre blowouts during enduro races.

[Busky2k]

Trust me, theres no way you'd be splittin H2O in your tires. )) (Drawing some vague knowledge from uni chem) H2O just wont spontaneously split in 2 on its own without some sort of chemical or metallic catalyst or current.

To put this into perspective, to get N2O (Nawwss) to split into nitrogen and oxygen spontaneously, it needs to be exposed in combustion chamber (1000C) for it to give you the O2 to give you the 'go'. Unfortunately even so, this aint the same with H2O. Tyres at 1000C anyone? Haha

Boiling water just means the water has changed from a liquid to a gaseous state. It doesnt mean the water is splitting up, or it wouldnt be water anymore would it? (Ie water vapour)

Edited October 29, 2005 by Busky2k

[Adrian Knack]

The increased temperature just means the molecules will move about faster and with more energy, which equates to a rise in pressure. You are not actually spliting the H20. PV = MrT is the equation P = Pressure, V = Volume, M = Molecules, T = Temp. and r is a constant.

From my understanding having N2 filled tyres only makes pressure more predictable and less changing under temperature changes. I have seen you can get it for road tyres now but can't see the value. Particularly at $9 a corner...

[Duncan]

BTW for those saying its good for race cars not road cars, I think its the opposite.

Its great for your average car driver, set it once when you put the tyres on, and throughout the tyre's life it won't change by more than 1 or 2 psi (assuming no leaks). Perfect for set and forget and you always get optimal tyre performance

On a race track on the other hand, you can expect to need to change the tyre pressures most sessions, and that means you would have to take nitrogen with you. For track use pressures on the same car are affected by the direction of the track (clockwise or anti), track temp that day, and even fine tuning of the car's balance.

[dangerous_daveo]

I remember back in the day my mate used to use it in his Gemini for racing, until they banned it. So to me that says it does something good.

[Wink]

I got my tyres filled with nitrogen mainly because of what Duncan said:

Its great for your average car driver, set it once when you put the tyres on, and throughout the tyre's life it won't change by more than 1 or 2 psi (assuming no leaks). Perfect for set and forget and you always get optimal tyre performance

[d00dz]

I got my tyres filled with nitrogen mainly because of what Duncan said:

<{POST_SNAPBACK}>

u did? how much for one fill?

[Adrian Knack]

But does it work? Have your pressures changed?

Could you please do a measure now and post what pressure you put in, what it is now and the time frame? I am currious to see if this actually works or not.

[Sydneykid]

Real world experiences;

I know that on a humid race day we have to bleed off more pressure in the tyres (as they heatup) than on a dry day. Note that is using a compressor with no water filter to pump up the tyres. I always put that down to more water vapour in the air. Not water itself.

I know that using air from a cylinder we still have to bleed off pressure in the tyres, just not as much as what we do out of the compressor. I always put that down to less (maybe even zero) water vapour in the cylinder.

I know that nitrogen filled tyres take even less bleeding off, I put that down to the lower expansion properties (due to heat) of the nitrogen versus air. ie oxygen (+ other gases) expands more when it is heated from ~20 degrees to ~70 degress. I don't know whether that is true or not, all I know is there is less expension from 100% nitrogen

cheers