Nitrogen in Tires

Amy Mindick · **Joined:** Fri Aug 29, 2003 11:10 am **Posts:** 53

Ok, A coworker mentioned a radio show she listened to this morning.
They were taking suggestions for improving fuel ecomony. One of the callers recommended using nitrogen to fill tires.
I did a brief websearch - found people selling the systems.
Any opinions, real-life use, etc?!?!
Is it some sort of hoax, seeing as 78% of air is Nitrogen anyway??

Wes Eargle · **Joined:** Mon Oct 27, 2003 9:47 am **Posts:** 3683

All that does is precludes any water from being in the tire, which means that there isn't any oxidation of the rubber from within, and that there is less pressure fluctuation.

And it's hard to completely purge plain air from the tire unless you have a double valve-stem wheel like the Kosei K-1.

Vincent Keene · **Posted:** Thu Nov 03, 2005 5:36 pm

Sounds like something along the same lines as using helium to make them "lighter". :lol:

Frank Catena · **Joined:** Wed Aug 27, 2003 1:08 pm **Posts:** 418

I've seen race teams use it so they can keep moisture out of the tire. They don't want to deal with the phase change that occurs when the water vapor boils at 100C. IIUC, nothing really special about nitrogen except that its readily available and inexpensive "dry" (sans water vapor).

Frank

DanDurusky · **Joined:** Sun Apr 10, 2005 7:31 pm **Posts:** 686

i thought people used nitrogen because its volume/pressure changed less w/ temperature than "air". no?

Richard Casto · **Posted:** Mon Nov 07, 2005 6:46 pm

DanDurusky wrote:

i thought people used nitrogen because its volume/pressure changed less w/ temperature than "air". no?

As mentioned above that is the reason. It is not so much that "air" is bad, but that "air" has moisture in it (which is what causes the larger pressure swings with temperature). And it is cheaper to put in dry nitrogen than it is dry air.

Todd Breakey · **Posted:** Mon Nov 07, 2005 10:16 pm

All the reasons above are the reasons that high altitude aircraft (Corporate and airliners) use nitrogen in their tires.

Arthur McDonald · **Joined:** Fri Aug 29, 2003 1:54 am **Posts:** 2052

To my knowledge, Miatas are not found at the same altitudes as corporate jets. Of course, you could launch one out of the hold of a C-117 at 40,000 ft, but that would be wrong.

I also doubt that tire temps will reach 100C in an autocross.

I kind of doubt you'll notice a difference.

This does remind me to mention that I received an invitation to attend a cocktail reception at Piedmont Triad Airport on the 16th to learn more about NetJets (fractional jet ownership) and Maybach (entire car ownership). If someone would like to come along with me, we can ask if they recommend nitrogen over their usual thin air

Todd Breakey · **Posted:** Mon Nov 07, 2005 11:50 pm

Art, we hosted a NetJets open house at RDU a couple of months ago. But instead of Maybachs it was Rolls Royces. LOTS OF MONEY walking around the lobby that day. More than normal that is. The Rollers were nice. Not sure about spending that much money on a car though.

Wes Eargle · **Joined:** Mon Oct 27, 2003 9:47 am **Posts:** 3683

Arthur McDonald wrote:

To my knowledge, Miatas are not found at the same altitudes as corporate jets. Of course, you could launch one out of the hold of a C-117 at 40,000 ft, but that would be wrong.

I also doubt that tire temps will reach 100C in an autocross.

I kind of doubt you'll notice a difference.

You're not boiling the water, you're increasing the vapor pressure of the water and making the tire pressure less predictable over a certain heat range, in addition to making the inside of the tire more prone to oxidation. That's why race car drivers do it.

Charlie Guthrie · **Joined:** Thu Aug 28, 2003 8:14 pm **Posts:** 832

A recent article in "Hydraulics & Pneumatics" trade magazine listed the main reason for using nitrogen in tires was maintaining more stable pressure due to the fact that nitrogen does not premeate the rubber tire as easily as plain air. Air has a high percentage of nitrogen, but also includes other gasses which can migrate through the rubber of the tire allowing the pressure to drop. This is a minor effect, and using an accurate air pressure gage and checking tires at least once a month is probably just as good for "economy". Using dry nitrogen would be the best. Water/moisture in tires is bad for a variety of reasons.
Charlie G

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Nitrogen in Tires

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