Nitrogen in tyres.

[Guest001]

For race car tyres we have several different processes. A simple double purge and refill gives 98% of the desired result ie; only leaves 2% of non nitrogen in the tyre. On some cars we have 2 valves, 180 degrees opposed, we fill from one with nitrogen while leaving the other open. That gives a 99% result. We also have an ex air con vacuum pump which when used to purge to minus 20 psi gives a similar 99% result. The results are judged by the tyre pressure increase when compared to a from zero fill (ie; at fitment) with nitrogen.


Cheers
Gary

I accept you do it right but for the average Joe he will go into a tyre place and they will probably pull the valve (if you are lucky) let tyre down and refit valve core and pump it up again. Still has air in it so whats the point.

Oh I forgot its to make money from suckers

[jimmedy]

Whilst I'm interested in the observation from Jimmedy above, I don't recall ever having issues with needing to constantly check tyre pressure a lot, or considerable drops in PSI that wasn't related to a puncture.

Yes, that's my assessment of things too - good tires well fitted to good rims shouldn't be leaking anyway.
I'm happy enough with a test of my thumb against the sidewall to alert me to any significant changes in pressure.

I do rotate and align every 10,000ish, and so my instructions are to check and top up, and the last two times they've told me there was basically no top up needed.

It's only this occasion that I'm waiting for a fitment of coilovers, ARB's and control arm bushings in the immediate future, I thought I'd get the alignment done after all that so I'm a couple of thousand k's 'overdue' based on my own schedule. That's the only reason I ended up at a servo checking pressure with their air hose.

It's a personal thing up to a point, and like I said, for $4 a corner, if even some of the associated claims are true, then I'm ok with that amount of money. But strangely enough for $8 a corner, like OP, I'd start to get suspicious.

Running at 40 psi, I don't want it climbing radically higher if I'm pushing it hard through the corners on a summer day, so if it just keeps the pressure more stable for me it's money well spent. YMMV.

[Sydneykid]

I accept you do it right but for the average Joe he will go into a tyre place and they will probably pull the valve (if you are lucky) let tyre down and refit valve core and pump it up again. Still has air in it so whats the point.

There are a couple off tricks that I have taught the tyre service outlets where I have done alignment product training courses at. If they are going to do a single valve purge and refill then they should do it when the tyre is hot, so the water vapour has a chance of being split onto oxygen and hydrogen. That applies whether they are doing a single or a double purge and refill. I suspect that the higher prices charged may relate to the number of purges and refills as well as drive time to warm up the tyres. Some tyre outlets do have dehumidifiers in their compressor process, so they should have less water vapour to purge.


Cheers
Gary

[alexaescht]

There are a couple off tricks that I have taught the tyre service outlets where I have done alignment product training courses at. If they are going to do a single valve purge and refill then they should do it when the tyre is hot, so the water vapour has a chance of being split onto oxygen and nitrogen. That applies whether they are doing a single or a double purge and refill. I suspect that the higher prices charged may relate to the number of purges and refills as well as drive time to warm up the tyres. Some tyre outlets do have dehumidifiers in their compressor process, so they should have less water vapour to purge.


Cheers
Gary

Oxygen and nitrogen? Water is made of two hydrogen atoms and one oxygen atom and heating water does not cause it to split up. Think about it, when you boil a kettle of water, the vapour that comes out as steam is water vapour, not hydrogen or oxygen as individual elements. Water will only split into hydrogen and oxygen through special processes. Heat will not do it.

[brad]

Howdy from the North. Just put nitrogen in all my tyres, recommended pressures. $30 at Bob Jane's. Go check after sale at any time, free FYI Nitrogen is an inert gas and does not increase/decrease with temperature, therefore only needs a check every 3 months, if that. Better tyre wear Ex. Aircraft Engineer

If you are an ex-aircraft engineer then you'll know that you don't take your vehicle to 10,000m / -50c.

Nitrogen on aircraft wheel assemblies is very good and has many benefits. Not so much on on motor vehicle wheel assemblies.

If it makes you feel good then that's great.

BTW, my local tyre place does it for $5/wheel

[kaanage]

Oxygen and nitrogen? Water is made of two hydrogen atoms and one oxygen atom and heating water does not cause it to split up. Think about it, when you boil a kettle of water, the vapour that comes out as steam is water vapour, not hydrogen or oxygen as individual elements. Water will only split into hydrogen and oxygen through special processes. Heat will not do it.

Yes, the benefit of removing the water vapour is that the vapour pressure rises exponentially with temperature, rather than linearly from a base of ~ -273 deg C as ideal gasses behave (which nitrogen and most of the other gasses composing "air" approximate well at the temperatures that car tyres face). This is why the tyre pressures are so much more temperature stable with nitrogen fill.

[alexaescht]

Yes, the benefit of removing the water vapour is that the vapour pressure rises exponentially with temperature, rather than linearly from a base of ~ -273 deg C as ideal gasses behave (which nitrogen and most of the other gasses composing "air" approximate well at the temperatures that car tyres face). This is why the tyre pressures are so much more temperature stable with nitrogen fill.

I understand that. I was pointing out that Sydneykid's analysis of making the tyre hot to allow the water to 'split into nitrogen and oxygen' is totally incorrect. That doesn't happen.

[wai]

Of course, one of the reasons it is used in aircraft (and racing) is that the last thing you want in an accident that results in a fire is a pressurised source of air with oxygen to help fuel any fire.

Nitrogen is also used in racing to operate the rattle guns. Again, you do not want high pressure air available where you are handling fuel.

For road use, there is no benefit.

[kaanage]

I understand that. I was pointing out that Sydneykid's analysis of making the tyre hot to allow the water to 'split into nitrogen and oxygen' is totally incorrect. That doesn't happen.

Of course. I was also commenting for Sydneykid

[Hail22]