My local Porsche dealer is trying to sell me "nitrofill" where they replace the air in the tires with nitrogen. They claim that it increases tread life, improves handling and braking, etc. Doe sanyone have any experience with this.

Thanks

 

if you belong to Costco, they will fill them with nitrogen for free.

 

There was a recent discussion about this at the PCA SDR forums:
http://forum.pcasdr.org/forum/viewtopic.php?t=2031

 

I use it in my race cars but don't really worry about it in my street car although its certainly not a bad idea. The value of nitrogen is that it's dry. Air has a lot of moisture.

Don't let the dealer rip you off too badly. They are paying about a 50 cents for enough nitrogen to fill your tires.

 

I'm surprised at the performance claims. Never heard that before. But I can say that I used nitrogen in my truck's tires one year, and there is no question that they held their pressure for longer. The pitch I got was simply that because nitrogen molecules are larger, the gas in the tire doesn't seep out the way air will. That's how it worked for me... pressures that had to be checked and corrected at least monthly in the truck were now holding steady for the entire season. There was also a claim that nitro was more thermally stable, so pressures wouldn't change with temperature. I can't verify that with the same confidence, though.

FWIW...

 

I heard nitrogen is less affected by temperature than air causing less fluctuation in tire pressures.

 

This makes me laugh more than the RSS plenum stuff :-)
Air is about 78% Nitrogen anyway and about 20% Oxygen... trace Co2 water vapor He etc
N2 is Atomic mass 28... O2 is atomic mass 32... so Air and N2 are almost the same "molecule size"
All gases obey the gas laws, so they all change pressure with temperature. PV (proportional to) T

Jim B has this one nailed... its just the water vapour.... Clean Dry Air or Clean Dry Nitrogen should be exactly the same.

But hey if you want to buy really expensive air :-)

 

I heard that Viagra also makes you blind

 

Okay, so school me: Because I'm **** about tire pressures, and the rears on my Rover need frequent checking because they're supposed to be kept at 46psi. Why did the nitrogen filled tires not need pressure corrections for a whole winter? I was buying the molecule story, but this ain't my expertise. So how did it work? (BTW, I have no skin in this. The tire guys used nitrogen accidentally and didn't charge me).

 

Perhaps they re-seated the valve stems better when they re-filled... any small particles on the valve seat would cause a small leak... cleaner N2 with a better filter perhaps ?

Water vapour will condense on the tire walls when they are cold (not contribute to the pressure in the same way), so you should see more stable performance from a dryer gas

 

*shrug* Maybe that small difference in atomic mass is enough, because I can't explain it otherwise. I've had the truck for a long time, tires come on and off twice a year, I check pressures every two weeks. This wasn't some fluky thing where in only one season out of many, four tires and valve stems were miraculously mounted better where they never had been before (nor since). It was materially, measurably, empirically different. Like I said, no axe to grind here. I've never bothered putting it in since, but I'm here to tell ya... on that truck, with those tires, that season, I didn't lose any pressure for more than three months. Gotta be a reason.

Thanks for the response.

 

Bruce,
Interesting observations.....

This is a huge debate on some geeks science site too.

http://www.eng-tips.com/viewthread.c...=120996&page=1

Heres a thought..... Perhaps the O2 reacts with the rubber tire insides to slowly get consumed ? N2 is much more inert and wouldnt react. This would limit to max pressure loss to 20% as by that point all the O2 would be reacted with the rubber.?

Thanks

 

I have nitrogen in my tires, courtesy of Princeton Porsche. While it's normally a $70 service, our region held its monthly meeting there and the service was provided free to anyone who attended and wanted to try it.

In driving my car since then, I find no perceptible difference in handling, breaking, steering, or acceleration. The tire pressure in each tire is holding steady, and perhaps that's a benefit.

So far, I don't yet see enough information on this thread for me to advocate its use, or to be skeptical about the benefits.

 

There is no difference. It's all pretty much imaged. (Myth-Busters proved it recently). Since air is 78% nitrogen to start with can you possibly feel that 22% difference? Some like to say that the nitrogen molecules stay inside those osmopic tire membrains,--rubbish! I rarely add air to my tires and with the built in TPMS in my car I can see that they are always spot on from day to day, week to week. I have literally not had to add a lb to my tires in nearly a year.

 

Well, I'm out of my depth, here. I only know what I've experienced, and I was prepared to believe it because I've lived for years with the fact that bikes lose air from their tires, like, every couple of days. (I realize that bike tubes are butyl, which is porous, and I only assumed that it was generally true for rubber, but never really thought about it).

Edgy, cool that you don't have to add air to your tires regularly. The constant climate of CA must help a lot. I've never owned a car that didn't need some kind of pressure adjustment every couple of months at the very least. Mind you, I'm one of those **** types that carries a tire gage in every car...

Anyhoo, file me in the unexplained phenomenon folder. Beats me, and I've never bothered using it again anyway.