Nitrogen to inflate tyres?

[anthonym]

What's this about? Will it help address my altitude issues and is it cost practical?

[rj]

It's more about avoiding moisture inside the tyres - to prevent the pressure to change across the temperature.

[Myles]

...as to the cost, I *think* I remember seeing it as an option in the local fitters for around £1 a tyre. It certainly wasn't expensive, but whether it is worth it, I dunno.

 

FWIW, when I got my latest set of tyres/wheels back from the fitters and was reducing the pressure from 30+psi to the high teens needed for the seven, I did notice what appeared to be quite an unusual amount of moisture being blasted out of the valve of one of them (spitting slightly - not a jet!). Dunno the source or extent - but if that was the norm, I'd possibly possibly consider it for a quid.

[DohNut]

 

Do you know a scuba diver?

 

The compressed air is dried to remove condensed moisture and to make it nice to breath does not have any oil in it.

You can get a low pressure inflator to use with car and bike tyres.

Been meaning to get one for ages - annoys me to be using a pump and having cylinders of compressed air sitting next door.

 

a garage compressor will be somewhat dry but much less so as the resevoir is a much lower pressure the effect is reduced. it will also have some oil in the air.

 

Nick

 

[myothercarsa2cv]

I use a mix: 78% Nitrogen, 21% Oxygen, 1% random mix. Seems to work well.

[gileshudson]

😬

[richy]

a garage compressor will be somewhat dry but much less so as the resevoir is a much lower pressure the effect is reduced. it will also have some oil in the air.

In my experience, garage/tyre fitter's compressed air receivers are very often full of water as the condensate quickly builds up and is not drained regularly.

[Jonathan Kay]

I think that filling car tyres with nitrogen is mostly a fashion issue, but

 

1 The reduced water content is a genuine reason for its use in aircraft. It seems to be cheaper to buy nitrogen, which is inherently dry, than to dry compressed air.

 

2 The reduced water content may be a genuine reason in some very critical applications that need controllable pressure-temperature-volume relations, such as Formula 1 tyres

 

3 The absence of oxygen and reduced risk of fire is a genuine reason for using it in the late Space Shuttle.

 

4 The diffusion argument is guff.

 

5 The inertness protecting your wheels argument is guff.

 

Jonathan

 

Edited by - Jonathan Kay on 24 Aug 2011 13:14:49

 

Edited by - Jonathan Kay on 24 Aug 2011 19:41:04

[Bricol]

Still only seen them add extra nitrogen, never fill with nitrogen.

 

😬

 

Bri

[Krismuss]

They gave me nice kawasaki green valve caps (to match my car) when they filled mine with nitrogen at ATS! 😬

[Roger Ford]

ATS say you can get 15% better fuel consumption with nitrogen in you tyres. Or rather they used to say that, but the ASA upheld my complaint 😬

[Piers Rendell]

In Egypt last year, I found out that tyres out there are filled with nitrogen. Is this something to do with high ambient temperature ?

[colindavies56]

also,its lighter than air,and,its bubbles are bigger so will help with leaking valves,or leaking side walls.

[Sheds Moderator]

N2 isn't significantly lighter than air, that's a sales pitch. Air is 80% N2 anyway, the rest is oxygen (O2) and trace amounts of other gases. 24 litres of N2 at standard temp and pressure weighs 28g, pressurised to 1 barg it will be 56g. Air comes in at 28.8g at STP, pressurised to 1 bar 57.6g. That's a difference of 1.6g per 24 litres. Tyre have a tiny fraction of this, say 5 litres tops. Say a difference of 0.3g. Your dust cap weighs more than that.

[Jonathan Kay]

I've been trying to work out why this is promoted... the additional profit from the inflation with nitrogen must be tiny.

 

The interweb came up with one suggestion: you get the first inflation, then you feel you have to take it back to the first place fro the top-up, then when you need new tyres you naturally go back to the same place.

 

Unless you can think of anything more plausible...

 

Jonathan

 

[Jonathan Kay]

pressurised to 1 barg it will be 56g

 

I thought that was a typo, but now I know all about gauge pressure

 

Thanks

 

Jonathan

[Rob Morris]

More stable, less expansion with heat............NOT much advantage to Mr Average road car

 

[Dignity]

Helium

You can tell when someones using it as their tyres have a higher pitch squeal when cornering 😶‍🌫️

[rj]

Helium is no good due to the small molecules - it will escape like it does through a balloon.

[CageyH]

Nitrogen

I use it in all my tyres at work.

However, they are inflated to around 13.5 bar.

[Roger King]

Other than very small variations, gases all behave as ideal gases, which means that to all intents and purposes any gas will increase the tyre pressure by the same amount for a given rise in temperature.

 

Can someone explain this idea that nitrogen expands less than air when it gets warm? Or is it really moisture in the air that nitrogen eliminates - or is it snake oil?

[Sheds Moderator]

I suspect it is both. Both less moisture and snake oil. No doubt it is drier and I suspect the difference unless you are Lewis Hamilton is 3/10 of bugger all.

[rj]

As the air we breathe contains 78% nitrogen it is just down to the moisture. There's a component of snake oil too, but there will be a (not very significant) difference.

[Jonathan Kay]

Can someone explain this idea that nitrogen expands less than air when it gets warm? Or is it really moisture in the air that nitrogen eliminates - or is it snake oil?

 

There is a genuine effect of not having the water there. That's why they use nitrogen in aircraft tyres. As far as I can tell from then on the logic fails when the effect is attributed to the presence of nitrogen/ lack of oxygen rather than the absence of water.

 

Mostly snake oil for most car uses.

 

Jonathan

[Jonathan Kay]

I use it in all my tyres at work.

However, they are inflated to around 13.5 bar.

 

Is the Wikipedia section on aircraft tyres accurate?

 

Thanks

 

Jonathan