S40 (New) Wheels/Tyres : Nitrogen inflated tyres ? Does it really work?

[jadatis]

I kept myself busy with tyre-pressure-calculation, with use of the formula the European tyre-makers also use for decades. In my search for info came to a new better one, but also came to know something about Nytrogen-filling.
Found this post searching Google for tyre-pressure, and dont have a Volvo, so wont introduce myself in an opening topic. I am Dutch so sorry for miss-spelling and strange words.

First: every gas expands the same with the temperature ( not butane because it gets liqiuid at 4dg C) .

Nitrogen takes more energy to heat up, so at the short moment mayby a little colder, but at the long term the same inside-tyre-temperature as Air (about 20% oxigen,80% nitrogenium).

CO2 will react with the rubber so its gets sponchy, so we cant use it- .

the production of 100% Nitrogenium ( further N2) makes that there is no water in it, wich reacts unpredictable with temperature, for the same reason as butane, with the temperature there is more or less watergas in the tire, parts condence to water.

The highening up of the pressure in the beginning can be explained by the partial pressure of the different gasses in the tyre.
The diferent gasses go their own way in difusing trough the tire.
There is constantly going O2(oxigen) and N2 going in and out the tyre.
How fast depends on the pressure.

I will try to explain this with an Example:
You fill the tyre to 3 bar with N2, the empty tire has 80%N2 and 20%O2 of the same pressure as the outside=1 bar. You fill with 100% N2 of 3 bar to the pressure of 4 bar in the tire, What you measure is 3 bar overpressure over the outside pressure. Then the partial pressure comes up ( further Pp).
Outside the tire PpO2= 20% 0f 1 bar =0.2 bar and the PpN2=80% of 1 bar =0.8 bar.
Inside the tire is PpO2= 0,2 bar+3bar*zero=0.2 bar PpO2 and PPN2=0.8bar+ 3*1Bar N2=3.8 bar PpN2. Pp O2+N2 makes 4 bar again( measure 3 bar overpressure).
Then in time O2 goes yust as fast in then out the tire because Pp is the same inside and out. Then there is per saldo only N2 going out of the tire. even the pressure gets lower the PpO2 stays the same but the percentage O2 in the tire goes up.

If you manage to get the PpO2 lower in the tyre, by filling it for instance to 4 bar overpressure and letting out air to 2 bar , and that in a few sessions , you can bring PpO2 back to mayby 0.05 bar in the tyre.
Then the PpN2 is 3.95 bar in the tire . outside stays the same.
Then the PpO2 is more on the outside then on the inside ( out 0.2,in0.05)
Then when the N2 is per saldo going out the tyre, the O2 per saldo is going in the tyre. And because O2 goes about 5 times faster trough the tyre then the N2 goes out , the pressure can get a bit higher in the beginning.
But it wont be much , so checking it is not needed to my opinion.
At a sertain point there is a new balance for the PpO2, Inside and outside Pp is the same then. So the system works itself to a sertain persentage O2 depending on the real pressure in the tire.
I worked with Bar , because calculations stay simple because of the outsidepressure expressed in bar , 1 bar is about 14.? psi.

If you want to read more about tire-pressure, look into my public map on skydrive.
https://skydrive.live.com/?cid=a526e...E092E6DC%21128
Also an article of J.C.Daws about a new way of calculating,with in my own reaction link to his site where article about N2 with proove of this story.
To open a document: Click on the I in a cirlce at the end of the line, then in the right bar info appears about it ( with the reactions also) , Press Download , and after downloading open spreadsheets in Excell or compatible programm.

Greatings from Holland and sorry for the long story.
Peter

[SonyVaio]

Originally Posted by jadatis

Greatings from Holland and sorry for the long story.
Peter

Grat insight there Peter, thank you and I'll be downloading from your skydrive soon. to the forum by the way.

But what do you think for normal going road cars? Does it really provide any great benifits and if you had to pay for N2 inflated tyres would you pay?

[popuptoaster]

My dad has been having Nitrogen put in his cabs for a couple of years, he says the tyres last longer but not by much, as he does two sets of tyres per cab per year though its worth it to him as long as the nitrogen is free.

[adey34]

Grand Prix Motorcycle race teams use Nitrogen because it keeps the tyre tempriture cooler and sustains a more even presure!

[jadatis]

Originally Posted by SonyVaio

Grat insight there Peter, thank you and I'll be downloading from your skydrive soon. to the forum by the way.

But what do you think for normal going road cars? Does it really provide any great benifits and if you had to pay for N2 inflated tyres would you pay?

I have had 3 ( also the spare) new tires on my caravan, and they asked if I wanted them filled with N2 , but it costed me extra, so I did.nt do it.
If it was for free , I would have sayd yes.
If you have N2 filled tires , and you have to fill on vacation, just do it with air, no problemm, better then to keep driving with to soft tires.
What I wrote about higher pressure when checking later, could more likely be because the tires where warm then, and when first put on cold. I dont think the going in of O2 compensates enaug the going out of the N2 , so by that alone the pressure would still be lower.There is still more N2 going out then O2, even when filled with normal air , because of the PpN2 then 4,0bar and the PpO2 0f 1 bar inside and out 0.2 and 0.8 , I estimate. Read somewhere that O2 goes 5 times as fast out then N2. How to calculate that in examples I dont know, but this last example I think . difference PpO2 0.8 bar , Diference PpN2 3.2 bar .
5 times (as fast) PpO2 0.8= 4 and 1 times PpN2 3.2=3.2 so ten a little more O2 out of the tire then N2 in the same time. But probably it isn't that simple.

Greatings again from Holland
Peter

[GMad]

Originally Posted by Paul Wildsmith

QUOTE:how does 100% nitrogen rather than normal air nitrogen at 78% make that much difference?

It doesn't!

[v50inred]

Haven't scanned the entire thread but apparently Nitrogen is less affected by temperature, so less change in pressure.

My V50 has Nitrogen inflated tyres, can't say I have noticed any difference, but then again the tyres where below proper pressure when I bought it and I had to put a few PSi in every tyre so maybe any advantage is lost now?


I suppose it can't hurt?


A bit like ZX1 perhaps, you may not notice a difference but the motorsport boys seem to find benefit.


Jadatis, thanks for bringing back the memories of partial pressures from my Training days many years ago, I thought I had fully recovered, one subject I really didn't "bond" with shall we say. Lol.

[Paul Wildsmith]

this is all fascinating, and in some ways remids me of something I remember reading years ago in an enthusiasts hi fi magazine (the sort that very much looked down on CDs when they first came in). Anyway, apparently making sure you had a 13amp fuse rather than a 3amp fuse in your amplifiers mains plug would make a difference to the sound!

Back to tyres - I find the main thing to prolong tyre life these days is to keep a sharp eye out for potholes. The fractional increase in using nitrogen rather than air is akin to rearranging the deckcahirs on the Titanic ...

Just a thought, how about using helium, and that surely must help in lightening unsprung weight?

[kebab10]

Might as well fill them with water by the sound of things.