Nitrogen in tires

[Uberman]

Hello again. I heard that putting nitrogen in the tires helps to stablize the pressure as compared to standard air. I understand that air has 78 percent nitrogen anyway and the nitrogen they put into tires is between 95-98 percent. I read that the difference is marginal at most and is a scam used by car dealerships to make additional money, but they do use them in race cars. Has anyone of you out there tried it in motorcycle tires? If so, what is your experience with it? Just curious.

Thanks,

Uberman

[RRider]

You nailed it. It is a scam. Some racers do use nitrogen in their tires but its benefit is mostly for control of the pressure increase that occurs when the tire heats up. In a race, hundredths of a second mean the difference between winning and losing, so those guys will do anything to maintain as much control over as much as they can with their vehicles.
I did go abandoned development riding with a guy that put nitrogen in his tires. I rode his bike and couldn't tell any difference. But he mostly used the nitrogen because he would keep a small bottle in the back of his pickup for quick fills/refills/topoffs if necessary.

[Uberman]

Cool. That's pretty much what I thought. Thanks for the info.

Uberman

[FreedomRider]

Just the other day I had to serve a subpoena for records on a local Hi-Performance franchise for Pick-Ups, SUVs, 4WDs etc. There on the sales counter was a 10x10 placard espousing the wondrous benefits to be had by paying a bunch of money for nitrogen filled tires over conventional free air from any o'l air pump.

As I previously said elsewhere in these forums
“If ever there was a demographic ripe for any kind of Captain Wizbang, time saving, and performance enhancing snake oil for a salesman and manufacturer to pilfer from it is the fraternity of automotive/motorcycling aficionados.”

[David_S_Walker]

Shame I can't use Methane.....

.....According to my good lady I have an endless personal supply of methane on tap

Good old air is just fine for me and is one of the few things in life that is (mostly) free

Best regards,

David

[TNK12S]

Here is a more theoretical but practical explanation:

Back in the days when dinosaurs (and I) roamed the planet and before modern tires were compounded using chlorobutyl and halobutyl inner linings there was a real concern about air pressure loss due to the fact that molded rubber was fairly porous and air migrated through the tire casings over time. To complicate matters, as casing rubber temperature increased, the rubber became more elastic and thus air could potentially seep at a higher rate than when cold. Since Nitrogen gas is a relatively larger molecule than oxygen, helium, and hydrogen it was believed that it would not seep as rapidly as the other smaller gas molecules.

<start boring theory>
The physics of pressure change over temperature is represented by the "Combined Gas Law": (P1 * V1) / T1 = (P2 * V2) /T2 and applies to all gasses and gas mixtures. (Yes, we could split hairs over the R-Factor from the Ideal Gas Law but I'm not going there.) Consequently, it makes little if no difference whether you inflate with air, helium, nitrogen or any other gas. Given constant volume, the behavior remains the same as your tire temperature increases regardless of which gas you use for inflation.
</end boring theory>

With the evolution of modern rubber chemistry tires are now constructed with layers of various rubber compounds, belting materials, and adhesives. The first layer applied to a tire building spindle is a thin but extremely dense layer of chlor- and/or halo-butyl rubber that acts as an "impervious" barrier to air migration. Then, depending on the specification, various layers of other rubber compounds and materials are applied until the whole assembly is ready to be thrown into a mold and cured. This significantly improved general air loss from seepage but didn't completely solve the problem because any damage to the inner liner (usually because of mishandling by a dealer or consumer) would reintroduce seepage at the damage points.

The real problems with air loss are twofold. First, low pressure tires flex more creating a higher heat build up especially in the casing sidewalls. When the heat builds up high enough the adhesives used to bond the belting package to the rubber start to decompose, the belt package starts to shift, the casing expands, and, voila, you get a blowout. Secondly, air migration is a problem because it can seep between the plys and create ply separations that will also lead to blowouts.

Just as important, most compressed air contains moisture and oils (from oil misters installed to operate air tools). These are bad actors on tires as hot moisture will hydrolyze various compounds in tires if allowed to migrate while the oil will act as "plasticizer" or softener. (In fact, if you have picked up a tire cut on the outside of the tire that exposes the belting, you should immediately repair or replace it to prevent road/rain water from entering the belt package otherwise you greatly increase the risk of a catastrophic casing failure.) Thus, the valid reason for using nitrogen is that it is fairly cheap, comes compressed in a bottle that is relatively easy to transport to the track, and contains no water vapor or oils that could adversely compromise your tire casing compounds.

How many times have you cracked the pressure on your airline and watched a cone of water vapor blast from the end of the hose? This is why people install dehydrators on the discharge side of their compressors which absorb and/or condense out 99.9% of water vapor and other possible contaminants.

So the bottom line is this: dry, contaminant free gases are best for your tires whether those gases are air, nitrogen, or some other inert combination.

[RRider]

Thus, the valid reason for using nitrogen is that it is fairly cheap, comes compressed in a bottle that is relatively easy to transport to the track, and contains no water vapor or oils that could adversely compromise your tire casing compounds.

TNK12S is correct in his more theoretical but practical explanation and if a person is racing or going out to the track quite often I, in theory, recommend (that's all I'm doing, recommending) using nitrogen from a bottle. In my previous post I mentioned that I went riding with a person that kept a bottle of nitrogen in his truck. And it was great; fast fill ups, even had plenty of pressure to pop the bead back on when he had to replace a tire. BUT. He worked in a welding shop. They used lots of gas for the MiG and TiG welders. He simply added a tank of nitrogen to the weekly order when "his" bottle ran low. If anybody were to check around with some of the gas supply places they would find that even though the nitrogen itself is fairly cheap, the cost of the bottles gets very expensive. For instance, to lease a bottle from the company costs between $1.75~$3.75 a day plus the deposit and one doesn't get credit for returning the gas. If one doesn't go riding that much and it takes....say....3 months to empty the bottle, that gets just a bit expensive. One could purchase a bottle-$$$$-then there is the hassle of making sure that it remains certified (safety and pressure testing-mo' $$$$) and one would then have to take the bottle to the fill depot to get it filled (9-5 weekdays only). Of course, one also has to have a truck or car set up to transport the bottle. I personally will just make certain that I keep my tires filled to their proper pressure with air.

Please, Readers Of This Post, do not think that I am condemning the use of nitrogen in one's tires "across the board". Take the example of my acquaintance: he had a truck, he had a motorcycle that he used mostly for playing around on, he had another bike that he mostly used for street/daily riding and he was able to get nitrogen delivered to his place of employment on a regular basis for a negligable cost (free delivery, approx. $20 a bottle and, because of the volume of business his employer did with the welding gas company, no lease fees). I am certain that clubs could spread the cost of the nitrogen so that it was negligable for the members. On the other hand, someone doing this by himself....probably not.....

FWIW, I have a separator and filter that I rescued from the scrap heap, screwed together with pipe nipples, attached a quick disconnect on the input side and a 4' length of hose on the output side with a tire fitting on the end that I use when I am worried about the quality of the air coming from a gas station's or someone's compressor.

[Streaker]

Tried to reply to this thread a while ago, but comp crashed. I work with nitrogen in tyres and so have an endless supply (that 747 you flew on might have been one of mine, kidding) In aviation there are two reasons we use nitrogen, first it doesn't support combustion and secondly it is dry air so no corrosion on the rims. I have used nitrogen in my bike tyres since 1999 and compressed air since I was a kid on a bicycle (legally). However at the track I use compressed air, purely because of its availability. So far, there is no noticable diffrence between the two both in handeling and tyre wear. As a point in question, when a tyre rep from a very popular brand was asked to explain how nitrogen allow tyres to last longer on my bike on the exact same road surface ie grade of friction he couldn't prove a diffrence. So personal opinion use what is at hand for convienance sake.

[Mowster]

Yes; BUMP!!!

What I really want to know is:

Can there be a real difference in the increase of pressure due to heat when using 100 % nitrogen?(or any dry inert gas)
(i.e. inflate, purge, inflate again for highest percentage)

When I go to a track day, the specialists at Phillip Island Racetrack (probably the fastest in the world!) advise to reduce pressure to 30psi, or even less, due to the high average speeds, and consequent high tyre temps.

On my K1300R, the manufacturers recommendation is, of course, 36 and 42 psi.

I dont want to reduce pressures so much.

When you do 15 - 20 minute sessions, and you dont have tyre warmers, it seems that a more stable tyre pressure cold-hot ratio is a good thing.

Doing 2 - 3 laps slowly to warm the tyres, and theoretically get the pressure up to what is supposed to be "operating pressure", seems to be introducing too much uncertainty.
As the BMW tyre-pressure monitoring system is temperature-compensated, it is no real help.

If you think nitrogen is nonsense, what should cold pressure's be, before going on a really brutal ride??????

[Doug]

If you want to try nitogen a cheap place to get is is at some paint ball ranges- some guys use it in highend paint ball guns- You would need an adaptor from the paint ball fill end to a bike tyre- I used to use nitrogen in my Cessa wheels - dont know if it made a dif. at all but I had a nitrogen botle for my paint ball gun anyway

[Mowster]

Heck, I can get aviation grade N2 from work easily......

So, i'll experiment at the next track day and report back.....