Continuation Of Nitrogen Tyre Fill

[TigerFish]

When i went to the Time Attack at Donington park with Prolex the tyres that he had on the IS350 were filled with standard air and shot up in pressure after a couple of laps, We had set Dave's tyres all round to 35psi and after 2 laps they were reading at 45-48psi and i had a reading from the rears at 50psi at one point in the day, :o I never realised that tyre pressures would get that high which now helps me understand why blow outs in tyres happen a lot more on the motorways due to the heat of the tyres and the rising pressures?

At Silverstone Dave had his tyres filled with Nitrogen, again set at 35psi and after 10 or more laps they had only gone up in pressure by 1-2psi the highest reading i got on the day was 37psi which showed quite a difference in the use of Nitrogen on the track? Not sure how much it would effect a car on the normal roads though, so basicaly we found that tyres filled with nitrogen don't seem to increase the actual pressure like they would if filled with normal air? Must be more stable to heat but not sure how it works but just thought i'd let you know what we found out by using Nitrogen instead of air :D

slightly

Irrespective of the technical opinions, rights and wrongs etc , if the results are as stark acroos the board as

Dave has had on the IS350S/C then it's a no brainer.

Luckily mine were done some time ago @ WIM

BTW Dave those Brembos look awesome :D

Just wanted to continue this discussion as the results on face value are potentially somewhat floored (as Rob had touched on in the other topic).

@ Aztec, what were the ambient track temperatures at Donnington and Silverstone? I'm guessing that as pressures were logged, so were track & air temperatures. They are of course two totally different circuits with different corners and characteristics, so therefore it could be the track that influenced the tyre temperatures and pressures?? Which is kinda floored as far tests go.

@Wozza, The technicals must come into it to a degree, the results are not stark across the board without the test conditions being consistent, Assuming you are on about Aztecs post above??

[DJ Wozza]

yep :)

[aztecbandit1]

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[Sagitar]

I was just saying what happend when Dave used it? As i dont really care if its good or bad to be honest, plus it was snowing at Donny and quite warm and sunny at Silverstone so the track temps would be completley different and i'd of thought it would of been the other way round how the tyre pressures worked out with Silverstone being a lot warmer but not sure?

You need to look for another reason. The laws of physics are the laws of physics. Nitrogen and Air respond in the same way to temperature, pressure and volume changes. They both obey the standard gas laws. So, either the ambient conditions were different, or the rate at which the tyres were worked was different.

You could get a difference if very wet air was used to fill the tyre. But it would need to be wet enough to have free standing liquid in the tyre when it was cold. In that case, the water would turn to water vapour when the tyre heated up and cause a larger than normal change in pressure. It would be an unusual occurrence though, because air-lines for tyre inflation are normally fitted with water traps.

[Rob]

the only reason its used on aircraft by law is because its inert and will not fuel a brake fire if it happens - also the nitrogen we recieve is dryer than air so thats an advantage. It still changes temperature and tyres still looses pressure although i believe at a slower rate as the molecules are larger( i have to check that tho!)

[DJ Wozza]

I have no technical knowedge in this area (other than a 1986 physics 'B' @ O-Level)

but I was under the impression that Nitrogen resisted the heat build up/change in pressure etcbetter than air,

& hence the reason Formula 1 has been using it for years.

Like I said before I'm not any kind of expert, so be gentle when shooting me down,

I'm just passing on the info I have seen/read on the net over the years.

[Tony-Bones]

Food for thought.... Why does F1 use it?

[Rob's Lexx]

most people probably don't care about this sort of subject matter, but its close to my knowledge base and i think its only fair for everyone to see arguments from both a marketing side of things and a scientific side of things:

here's my 2pence worth.......

In my opinion, when considering something like tyre deflation rates/longevity of inflation and relating this to the gas within the matrix (in this case the tyre) the question that has to be asked is which will stay in the tyre the longest and not permeate through the sidewall etc etc.

now to answer that you need to think about the chemistry/physics underpinning the gasses involved.

lets say for arguements sake, that air is 75% nitrogen (N2 or divalent nitrogen) and the remainder for all intents and purposes is oxygen (O2 or divalent oxygen). Now it strikes me as very odd for someone to think that an extra 25% nitrogen will somehow improve the inflation/deflation time of the tyres.

why is that the case??

- well as sagitar has mentioned, Boyles Law (or ideal gas law: PV = nRT) applies to perfect gases, of which both N2 and O2 are. As mentioned, only very moist air (unlikely to be the case from a compressor etc) could cause an appreciable difference in pressures between the two.

- molecular mass and density of nitrogen is LOWER than that for oxygen. This means that in theory oxygen will stay within the tyre for longer

- atomic, covalent and van der walls radii of divalent oxygen and divalent nitrogen are essentially the same. This means that neither oxygen or nitrogen have a smaller natively abundant molecule (they are the same size). This throws the codswallop theory of "its a larger molecule so it doesn't seep out as quickly or as readily" straight out the window.

everyone is entitled to their own opinion of course, but unless i'm overlooking something obvious, I see no real benefit from N2 filled tyres at all. In fact, quite the opposite: based on density alone (as thats the only real difference between the two from a physical point of view) air would actually stay in the tyre for longer - but i'd seriously doubt there would be any significant difference between the two.

If it was the case of molecule size (as mentioned in a previous thread), why not use Argon?? Its just as inert and a lot bigger than nitrogen......

@Tony, no idea why F1 use nitrogen in their tyres. I guess if you really wanted to be finnicky over it, you could argue that the tyres would be ever so very tiny winy lighter than air filled. but i don't know to be honest. there must be some decent reason......

[Tony-Bones]

Please understand i am in no way offended, just want to do the best for my customers..... But the question still remains, why in the multi-million pound industry of F1 why do they feel Nitrogen is an advantage?

[redz_UK]

cant argue with science so unless somebody has a counter science argumnet thats it reallY!! all seems fairly logical to me.

as for why F1 use it, well its less prone to catch fire as we have been told and possibly ever so slightly lighter nad that would make a diff on an F1 car though..

although i cant see how this would make any diff on a road car seeing as how we all carry load of junk in our trunk!! im thinking subs amps, spare wheels and so on in case naybody gets the wrong idea about junk in the trunk!

[Tony-Bones]

cant argue with science so unless somebody has a counter science argumnet thats it reallY!! all seems fairly logical to me.

as for why F1 use it, well its less prone to catch fire as we have been told and possibly ever so slightly lighter nad that would make a diff on an F1 car though..

although i cant see how this would make any diff on a road car seeing as how we all carry load of junk in our trunk!! im thinking subs amps, spare wheels and so on in case naybody gets the wrong idea about junk in the trunk!

Given the option between air/ nitrogen if both were free which would you choose?

[DJ Wozza]

Given the option between air/ nitrogen if both were free which would you choose?

Free air in my lungs - Free Nitrogen in my Tyres :D

[Rob's Lexx]

hi tony.

the only advantage i can possibly see between the two is that air fed into a tyre from say a foot pump will have a slightly higher water vapour content (but we're not talking a lot here - maybe a gnat's foot). Obviously, as long as the nitrogen used is 'dried' then the water content will be that little bit less.

BUT, i don't think that its anywhere near enough for a significant difference to be honest. and 'dried compressed air' is readily available from all gas suppliers (BOC etc etc).

If they were both free then i would go for air anyway, but i don't see the relevance.

I'm sure the cost for N2 tyre filling isn't free?? i'd be interested to know what the charge is as i've read reports of £1.20 - £2.00 a corner in some places across the country :o

[DJ Wozza]

I'm sure the cost for N2 tyre filling isn't free??

it is at WIM :winky:

[TigerFish]

I guess it begs the question, if all tyre fitting places get the same tyres at the same prices (once you play off the price matching), it could come down to merely a gimmick. i.e. Come to us 'cos we will pump your tyres up the same as an F1 team. Could make the difference to some.

I'm not aiming that at anyone, just an option/opinion.

Wouldn't mind knowing what the F1 reason is too mind you.

[Rob's Lexx]

I'm sure the cost for N2 tyre filling isn't free??

it is at WIM :winky:

wozza, how is it done at wim please??

[redz_UK]

cant argue with science so unless somebody has a counter science argumnet thats it reallY!! all seems fairly logical to me.

as for why F1 use it, well its less prone to catch fire as we have been told and possibly ever so slightly lighter nad that would make a diff on an F1 car though..

although i cant see how this would make any diff on a road car seeing as how we all carry load of junk in our trunk!! im thinking subs amps, spare wheels and so on in case naybody gets the wrong idea about junk in the trunk!

Given the option between air/ nitrogen if both were free which would you choose?

TBH if both free i would gove the nitrogen a go iff only fo rthe placebo effect and so i can say i use the same air as F1 cars in my tyres!!

as a free service at WIM i think its great so why not!!

do i get my tyres filled at the WIM meet then??

[Tony-Bones]

Few owners would go to BOC would they?....

In my opinion N2 will be the assassin of compressed air "eventually" since not all companies use a "dry air system"... At wim we only use N2 and it's free.

Back to the F1 i'm afraid, i would love to read the official reason?

[DJ Wozza]

wozza, how is it done at wim please??

I'd suggest asking Tony, but the air is removed from the Tyres, then filled with Nitrogen

or so I understand it.

I must state that on my own car the pressures have remained very stable

since WIM fitted new Tyres for me recently.

[Rob's Lexx]

i'm not saying don't get it done, i'm just saying that i don't understand any logic behind it.

No Tony, no-one would go to BOC, but i presume your nitrogen source comes from somewhere???

take it its an evacuate/refill procedure for the nitrogen fill then based on that wozza. cheers mate, just wondered thats all.

[aaronabbott]

after reading this thread with great intrigue i spoke to a friend of the family who used to work for the f1 team mclaren and also jordan at the factorys and he said

normally filled with a special, nitrogen-rich air mixture, designed to minimise variations in tyre pressure with temperature. The mixture also retains the pressure longer than normal air would.

This is done for two reasons. Firstly the moisture content of air is variable depending on the local weather conditions and this differs considerably between some of the exotic locations on the GP calendar. By using dry nitrogen gas the tyres will behave in a predictable way wherever they are being used. The second reason is that air is a mixture of nitrogen (78%) and oxygen (21%). Oxygen gas is far more reactive than nitrogen and at the high operating temperatures of F1 tyres (> 100°C) the oxygen reacts with the tyre, reducing the total pressure inside.

hope this information helps :)

[Rob's Lexx]

yes mate you are correct, oxygen is more reactive than nitrogen, but on a road/occasional track car there is going to be absoloutly no difference. remember, there is oxygen outside the tyre as well and so any oxidation of rubber etc is just as likely.....

forumla 1 is a different kettle of fish to any road car. the boundaries are pushed to absoloute extremes and components limited out. anything that may help is a bonus. with regards to your mates comment regarding minimising pressure variations with temperatures, its not correct - air and nitrogen will occupy the same volume/pressure regardless.

The moisture content is the only difference between the two, but the fact of the matter is that dry air could be used just as effectively and its just as cheap as a nitrogen cylinder.

if you really wanted to use something that may help, argon would be the better choice, but the results either way are going to be so small you couldn't compare quantitatively.

there's a prof. in automotive engineering where i work who did some collaborative work with afriend of mine looking into this sort of thing and their findings showed no conclusive benefit at all......

[Dave-Ellen]

all i can say is my pressures with normal air were way higher after 15 minutes on track..............filled with notrogen nitrogen even temp rise was minimal and day was hotter as well

[DJ Wozza]

well if it's good enough for Formula 1 for years, and where I had it done is free,

then I'm a happy bunny

[Rob's Lexx]

wozza, you seem to be missing the point i'm trying to get at mate.

if someone is selling something that is meant to be beneficial for the buyer, then they should have a full understanding etc of why its the case.

i could tell u that putting ribena in ur radiator would increase its life but without any logical explanation etc no-one's gonna believe a word of it, especially if laws of science say its cobblers!!

@Dave, without proper testing on same track, same temps, same stresses etc, any observations are meaningless.

it may seem like i'm completely against this whole thing, and to some extent i am but that's simply because i do not, as a chemist, understand any logical basis behind it. If there is sound reasoning then fair enough and i'm all for improvements in industry techniques available to the consumer, but this, i fear, is not one of them.

To be honest, i'm not too fussed what F1 use in their tyres, they may well use N2 as a 'standard' instead of say dried air. If their operating temps are so high that dibvalent oxygen becomes reactive enough with tyre composites then thats a valid and safe precaution to take. I'm no expert on tyre composition, but unless there's much thia/thio moieties in the material, i doubt its gonna be any real problem.