Nitrogen filled tyres.

[Markymark-RS4-B7]

Just had my wheels balanced at ATS and decided to get the tyres filled with Nitrogen at the same time just to give it a go as I've never tried it before. I have to admit you really can notice a difference. I was sceptical before but you can definitely notice less road noise, the tyre pressure doesn't change at all almost when they got hot from hard driving and I'm not sure if it's just my imagination but the ride seems to feel a bit better too.

Has anyone done this and noticed much difference?

[adsgreen]

Yes - what you are describing is a well known thing called "the placebo effect".

This comes up so often we should get it made into a sticky so I've cut and pasted (and minor edited) the last conversation.

nitrogen expands the same as any other gas. The effect is called Charles law and is well known in thermodynamics (co2 filled tyres, n2 filled or even dehumidified air all expand the same amount). As such it doesn't matter what you fill the tyre with the pressure will be the same at a given temperature.
The issue is with water moisture which only comes into play when you approach 100c and it turns to steam. This transition to steam does cause a proportionally larger increase in pressure. However if you have road tyres hitting 100c internal temp on the street then you have other issues to deal with than a couple psi change.
Tried nitrogen and even on track I found it more a pita than anything else.

It's used in racing purely to give consistent behaviour - even then, some teams prefer CO2 and some N2.

Finally you don't have pure N2 in your tyres. Unless you could extract all the air out of the tyre (which you can't) or have a tyre with two air valves (one for air in and one for air out so the air can be cycled through until pure N2 comes out) the you will always have some residue of normal air. As such its not even what it really says it is.

[Markymark-RS4-B7]

Yes - what you are describing is a well known thing called "the placebo effect".

This comes up so often we should get it made into a sticky so I've cut and pasted (and minor edited) the last conversation.

nitrogen expands the same as any other gas. The effect is called Charles law and is well known in thermodynamics (co2 filled tyres, n2 filled or even dehumidified air all expand the same amount). As such it doesn't matter what you fill the tyre with the pressure will be the same at a given temperature.
The issue is with water moisture which only comes into play when you approach 100c and it turns to steam. This transition to steam does cause a proportionally larger increase in pressure. However if you have road tyres hitting 100c internal temp on the street then you have other issues to deal with than a couple psi change.
Tried nitrogen and even on track I found it more a pita than anything else.

It's used in racing purely to give consistent behaviour - even then, some teams prefer CO2 and some N2.

Finally you don't have pure N2 in your tyres. Unless you could extract all the air out of the tyre (which you can't) or have a tyre with two air valves (one for air in and one for air out so the air can be cycled through until pure N2 comes out) the you will always have some residue of normal air. As such its not even what it really says it is.

Cheers, I thought it was probably the case. Didn't think to check previous posts for it, will do next time.

[pDkALO]

Yes - what you are describing is a well known thing called "the placebo effect".

+1

Last time I had tyres done, I had them filled with an 80% nitrogen mix *, and it's worked well for me so far.

* it's called "air" - its good stuff, and could catch on....

[redrsr]

Moisture in compressed air expands when tyre temp increases, I always use breathing air (advantage of being a part time dive instructor), being filtered and dried it expands much less (more stable tyre pressure), same as all bottled gases

[adsgreen]

Only near boiling point. With normal roa tyres on track you would be lucky to get anywhere near that.
With semi slicks and esp slick tyres then yes but not much and 99.9% of drivers won't notice this.

Dried air is fine but how do you fill the tyre? All road tyres I've seen have only one valve and as tyres are pretty rigid you can't squeeze the air out of them. Therefore you will never get the air dry unless you fill and empty several times (and even then not guaranteed).
Tyres designed for racing generally come with two valves so you can cycle the air through.

[adsgreen]

Actual testing
http://www.powertank.com/truth.or.hype/

[redrsr]

Only near boiling point. With normal roa tyres on track you would be lucky to get anywhere near that.
With semi slicks and esp slick tyres then yes but not much and 99.9% of drivers won't notice this.

Dried air is fine but how do you fill the tyre? All road tyres I've seen have only one valve and as tyres are pretty rigid you can't squeeze the air out of them. Therefore you will never get the air dry unless you fill and empty several times (and even then not guaranteed).
Tyres designed for racing generally come with two valves so you can cycle the air through.

Agree, most of my testing was with slicks on a 911 (tyres prone to heating up as proximity of engine/exhaust)
Tyre pressures with foot pump air difference (cold/hot) 6-7psi, nitrogen 3-4psi, dry air about the same, unfortunately all gases will expand when heated (Charles Law), always found the sweet spot on a slick was +/- 1psi, anyway of getting close to this was a benefit
Always fill/drain new tyres 5 times, only because I believe any remaining moisture after that will have little effect, filling them very easy, dive bottle with regulator and low pressure inflator, tyre inflator adapter plugs in that

The dive centre supplies air to Graypaul Ferrari for their race teams

[redrsr]

Actual testing
http://www.powertank.com/truth.or.hype/

Read somewhere that Iraq had WMD's too

[adsgreen]

Actual testing
http://www.powertank.com/truth.or.hype/

Read somewhere that Iraq had WMD's too

Awww.. and you was doing so well up until then.

[adsgreen]

Agree, most of my testing was with slicks on a 911 (tyres prone to heating up as proximity of engine/exhaust)
Tyre pressures with foot pump air difference (cold/hot) 6-7psi, nitrogen 3-4psi, dry air about the same, unfortunately all gases will expand when heated (Charles Law), always found the sweet spot on a slick was +/- 1psi, anyway of getting close to this was a benefit
Always fill/drain new tyres 5 times, only because I believe any remaining moisture after that will have little effect, filling them very easy, dive bottle with regulator and low pressure inflator, tyre inflator adapter plugs in that

The dive centre supplies air to Graypaul Ferrari for their race teams

Just to be 100% clear - I've never said there is no effect from moisture. And as you've have shown above the effect is very small (but yes, important in your very specific scenario) but it doesn't change the fact that for a road car nitrogen is beyond pointless.
Question - do you drain and refill your road car so many times with the same car and attention every time it needs a top up of air?

[redrsr]

No, just top them um up using small 1 lt bottle in the boot

The benefits are minimal, granted, but for me it's far easier to use a small dive cylinder than hook up the compressor
The truth......I wouldn't pay for nitrogen

[redrsr]

But what about helium, lightest gas that's that's practical (don't want the car to end up like the Hindenburg), should also reduce unsprung weight, cost a bit hard to swallow and they'd go flat in a day

[sonny]

Not worth getting for the road.

[Rick_RS4]

bullshit, waste of time, itll never be full of nitrogen as air will be in it when the tyre is put on.