Tyre Pressure for Yoko's with Nitrogen for trackdays??

[951]

Hi Guys,

Just about to have Yoko A048's fitted to my trackday wheels and it occurred to me that I wasn't 100% certain on pressures and given I can't just add a bit more Nitrogen at home thought I'd best ask quick!

I have initially told them 18 front and 22 rear. Will that be OK?

Thanks in advance.

Graham

[AMG Merc]

951 said:

Hi Guys,

Just about to have Yoko A048's fitted to my trackday wheels and it occurred to me that I wasn't 100% certain on pressures and given I can't just add a bit more Nitrogen at home thought I'd best ask quick!

I have initially told them 18 front and 22 rear. Will that be OK?

Thanks in advance.

Graham

I don't know Yokos but the OE SO3s are 18f/27r

[Gadgeroonie]

my advice is put a little bit more in that you need

then you can set them on the day by letting some out

[sundance002]

Gadgeroonie said:

my advice is put a little bit more in that you need

then you can set them on the day by letting some out

+1. It really doesn't make a diff nitro or air, the pressure remains the same, and its only 3% lighter than air, so won't make really any diff, might save 3 gram in weight, IMO start with 25 psi all round, then as gadge said adjust it when your there.

[GTO600]

sundance002 said:

Gadgeroonie said:

my advice is put a little bit more in that you need

then you can set them on the day by letting some out

+1. It really doesn't make a diff nitro or air, the pressure remains the same, and its only 3% lighter than air, so won't make really any diff, might save 3 gram in weight, IMO start with 25 psi all round, then as gadge said adjust it when your there.

The point of charging with Nitrogen is that it doesn't suffer from large fluctuations in pressure with change in temperature unlike compressed air therefore enabling you to maintain a more constant tyre pressure.

[951]

Thanks for the answers chaps.

As Kevin says, the point of using Nitrogen is just to avoid the big increase in pressure with track temps and the resulting cycle of dicking around letting pressure out until it's right so I was hoping to get them set to the correct pressure in advance.

Gadge & Sundance - yes overinflating and then letting some out would have been the best idea - doh! But I'd already asked for 18 & 22 and then got them to change it once so didn't want to mess them about again!

I ended up with 18 front and 24 rear so hopefully that will be high enough?

Regards

Graham

[Hollowpockets]

I had the hard compound and needed to drop to 10 fr and 14 rr cold as they heated up so much on the ring and spa, hadn't used them anywhere else in the dry.

Coming off track hot that was them up at about 20/24 psi.

Just used normal air though!

[sundance002]

GTO600 said:

The point of charging with Nitrogen is that it doesn't suffer from large fluctuations in pressure with change in temperature unlike compressed air therefore enabling you to maintain a more constant tyre pressure.

Sorry guys there is no evidence that supports that, all gasses act the same it's called gas law, the only diff found is nitrogen loses 1.3 psi less than air in loss of pressure over the same period of time. , FACT it will heat no faster, it's all old wife tales made by tyre fitting co to charge a fiver more than air costs, all scientific tests proved that. Google it, its very clear.

[Mike Tuckwood]

sundance002 said:

Sorry guys there is no evidence that supports that, all gasses act the same it's called gas law, the only diff found is nitrogen loses 1.3 psi less than air in loss of pressure over the same period of time. , FACT it will heat no faster, it's all old wife tales made by tyre fitting co to charge a fiver more than air costs, all scientific tests proved that. Google it, its very clear.

Absolutely correct. "Air" is 78% Nitrogen already anyway.



Mike.

[GTO600]

sundance002 said:

GTO600 said:

The point of charging with Nitrogen is that it doesn't suffer from large fluctuations in pressure with change in temperature unlike compressed air therefore enabling you to maintain a more constant tyre pressure.

Sorry guys there is no evidence that supports that, all gasses act the same it's called gas law, the only diff found is nitrogen loses 1.3 psi less than air in loss of pressure over the same period of time. , FACT it will heat no faster, it's all old wife tales made by tyre fitting co to charge a fiver more than air costs, all scientific tests proved that. Google it, its very clear.

I'm very aware of gas law, the point is that compressed air contains moisture & although at normal ambient temperatures the rate of pressure change to ambient will be very similar to nitrogen at higher temperatures as when on track the liquid water vaporizes to become a gas & it's volume expands therefore rising higher than a dry gas such as nitrogen, thus it's the presence of water in air in the tyre that contributes to wild pressure variations as the tyre temperature changes.
You will still see pressure changes when filled with nitrogen but the trye pressure should remain more constant than when filled with compressed air.

Edited by GTO600 on Wednesday 14th November 22:28

[GTO600]

Mike Tuckwood said:

Absolutely correct. "Air" is 78% Nitrogen already anyway.



Mike.

And the rest is !

[Mike Tuckwood]

GTO600 said:

And the rest is !

Oxygen (21%) Other (1%).
As Sundance says, Google it. Have a look here http://ahotcupofjoe.net/2008/07/nitrogen-filled-ti... for some "easy reading" on it.

The water element in an air filled tyre is absolutely monumentally minute, the pressure changes bought about by harder use will be probably 99.99% of the pressure changes that the tyre sees.

The main claims relating to the H2O element are usually levelled at the oxidising reactive nature. 9hands up anyone who has had to swap out a tyre , not because its worn down, but because the water (and or oxygen) in the tyre has rotted it from the inside).
If anyone here is thinking that the relative humidity within their tyre is going to affect tyre pressure/performance then I suggest they are misleading themselves and are on a pointless crusade with no payoff whatsoever?

IMHO of course.

Mike.

Edited by Mike Tuckwood on Wednesday 14th November 23:54

[GTO600]

Mike Tuckwood said:

Oxygen (21%) Other (1%).
As Sundance says, Google it. Have a look here http://ahotcupofjoe.net/2008/07/nitrogen-filled-ti... for some "easy reading" on it.


Mike.

Useless artical about an American car on the road, what's that got to do with a Racetrack. I really don't need to Google it Mike if you read my reply to Craig i've already answered the reason why Nitrogen is better than compressed air on track.

How's your car coming on ?

[Mike Tuckwood]

GTO600 said:

Useless artical about an American car on the road, what's that got to do with a Racetrack. I really don't need to Google it Mike if you read my reply to Craig i've already answered the reason why Nitrogen is better than compressed air on track.

How's your car coming on ?

Yup, just seen your answer, unfortunately though, its ill conspired and incorrect.
Car's doing OK thanks, making good progress. :-)




Mike.

[GTO600]

Mike Tuckwood said:

GTO600 said:

Useless artical about an American car on the road, what's that got to do with a Racetrack. I really don't need to Google it Mike if you read my reply to Craig i've already answered the reason why Nitrogen is better than compressed air on track.

How's your car coming on ?

Yup, just seen your answer, unfortunately though, its ill conspired and incorrect.
Car's doing OK thanks, making good progress. :-)




Mike.

Think you need to do some more surfing Mike about Racecars

http://ezinearticles.com/?Why-Are-Race-Car-Tyres-F...

http://curiosity.discovery.com/question/race-car-t...

http://www.grippy.co.uk/tyre-news/tag/race-car-tyr...

[Mike Tuckwood]

OK, before people start getting their knickers more twisted, lets clarify; the point I am proposing Kevin, is that the constituent parts of compressed air (I hope you will agree) are CIRCA 78% Nitrogen, 21% Oxygen and 1% others.

The potential for air to carry water is the relative humidity level. Contrary to the mention in the highly technical argument proposed by the bloke at "grippytyres".

Is it "better", In the realms of micro measuring, then probably yes. In the real world; not a chance that you'd ever see ANY difference in tyre presssure which couldn't be more readily attributed to other factors.

Lets be generous and allow air to carry 2% water...... (I'll let you do your own research into how likely 2% water in air is).
But anyway..... 2% water, How hot has that water got to become before it expands sufficiently to materially, or measurably affect tyre pressure...... (F1 tyres operate normally below 100 degrees C btw).

Despite you clearly thinking you have the answer by typing a simple search into google and then posting the links you stumble across that appear to suit the idea you want to promote, if you took the time to stop trying to be confrontational and thought about the physics of it, I think you might see that the argument you're thrusting forwards with vigour, doesn't <pun intended> hold water?

Mr grippy tyre (from your link) also suggests that Nitrogen expands at a different rate than air..... Air is 78% nitrogen, how much greater are you suggesting the expansion rate is of the other main constituent of air (oxygen) is, though this is a diversion from your claim that water is the key bad guy here?

I don't need to do any surfing about Race cars, I'll also be happy to back down on this point too if you simply just want to be right, regardless of any FACTS.

I hope you can see where I'm coming from on this?



Mike.

[GTO600]

Have just emailed all the race teams in the world to tell them they have all got it wrong...
Ah well you live & learn.

[andygtt]

GTO600 said:

Have just emailed all the race teams in the world to tell them they have all got it wrong...
Ah well you live & learn.

dont you love keyboard racers

personally Im going to stick to air in case I have a tom cruise incident and drive into a lake and need the air in the tyre to breath.... you have to consider these things lol

[igeorge]

If our Nobles were as sensitive to tyre pressure/rideheight then nitrogen would might be an advantage. But c'mon, we're talking about private tracking, not F1 trying to find that 0.1s

Ian

[951]

fk me - I wish I hadn't asked now

Obviously, I don't know if it makes much/any/not a jot of difference - but it can't be any worse and it hardly cost anything.

Not that I believe everything I read on the internet (or anywhere else for that matter!) but the official F1 website says :-

"Formula One tyres are normally filled with a special, nitrogen-rich air mixture, designed to minimise variations in tyre pressure with temperature".

http://www.formula1.com/inside_f1/understanding_th...

Who knows how much the "variations" are that they are concerned with, and how much they can be "minimised", but we do know how much our pressures change on track so lets not get stressed

Edited by 951 on Thursday 15th November 11:00