Hi,
I saw a piece on the news about using nitrogen to fill tires instead of regular air. It said nitrogen improves gas mileage. Does anyone know anything about this? It costs $8 per tire to remove the air and replace with nitrogen which they say maintains its pressure and the pressure doesnt fluctuate with road/tire temps etc.
Anne

This is what I found on an Internet search. Nitrogen is different from air in that it is less reactive with rubber (because there's no oxygen). But really:

- Tires don't last long enough to care much about deterioration from air on the inside (last I heard from a mfr was recommended replacement at no more than 7 years, I get about 3 or so before they're worn out).
- the "savings" they quote are based on the assumption that your tires are underinflated with air, but won't be with nitrogen. The reality is that your tires probably get underinflated because of small leaks, not by air going through the rubber. You're not gonna see any savings unless you check your tire pressure, in either case. So put air in your tires, check them to keep the pressure up.


http://www.parker.com/ead/cm2.asp?cmid=9087&

The Benefits to Using Nitrogen

• Consistent inflation pressure over longer periods
  - Nitrogen permeates through the tire at a rate of 35% slower that oxygen (air)
  - Under inflated tires flex and build up heat, breaking down the rubber over time
  - 60% of blowouts are caused by under inflation
  - Consistent inflation improves tread life
  - Vehicle handling is improved
• Longer Tire Life
  - Nitrogen is a dry gas which disperses heat more rapidly resulting in cooler running tires. This preserves the integrity of the rubber, belts, and bead
  - This inert gas also significantly slows the chemical aging process associated with oxygen and moisture (air)
• Improved fuel efficiency
  - Passenger cars realize 2-3 miles per gallon gains (4% on average*)
  - Trucks realize gains of 2+%
• At 4% fuel efficiency enhancement, the savings are significant to the car owner
  - At 4% on a vehicle with 20 mpg rating, this saves approximately 2.5 gallons per week based on 40 miles per day @ $1.90 per gallon that adds up to $228 savings per year
  
  Source: Tire Review, July 2004

Hi All:

___There is a lot of BS written by these experts … One of the advantages of air vs. pure N2 is with the heatup, there is a larger increase in tire pressure. From cold at 44 #’s for example, you may have a 48# pressure at noon out on the asphalt. No way is that going to hurt FE vs. N2 with its smaller increase. 4% increase in FE? Yah right. Tire wear … again, maybe with under inflation due to bleed off but that is it. Tire wear from the inside? Never saw that one take a tire out before Finally, $8.00 a tire? Thats nuts!

___Good Luck

___Wayne R. Gerdes
___Waynegerdes@earthlink.net

I think this is really nothing more when you come right down to it than a (Sells-Gimmick) and nothing else.

I think a person would be dollars ahead to simply increase their Tire-Pressure and gain the additional FE from that. Then the same person would save out of pocket expense for gas with their increase in FE.

HTH

Terry

Gotta throw the BS flag on this one. Our atmosphere is primarily nitrogen - about 75% of the air we breath is nitrogen if I remember correctly. So, since we are inflating our tires with air right out of the atmosphere (not pure oxygen), changing to 100% nitrogen would have a minimal impact on fuel efficiency, tire life, etc.

Only impact it would have would be on your wallet.

JMO.

Isn't the Internet a wonderful thing?

So, if 78% of air is nitrogen already, then the benefit of inflating tires with pure nitrogen has a maximum benefit of only 22% of what they'd like us to believe. And if oxygen really leaks out of tires faster than nitrogen in any meaningful way, then our tires would gradually become filled with nitrogen automatically anyhow (when you add air, to displace escaped oxygen, it's 78% nitrogen)!

Air Composition



The sea-level composition of air (in percent by volume at the temperature of 15°C and the pressure of 101325 Pa) is given below.
NameSymbolPercent by Volume
Nitrogen N2 78.084 %
Oxygen O2 20.9476 %
Argon Ar 0.934 %
Carbon Dioxide CO2 0.0314 %
Neon Ne 0.001818 %
Methane CH4 0.0002 %
Helium He 0.000524 %
Krypton Kr 0.000114 %
Hydrogen H2 0.00005 %
Xenon Xe 0.0000087 %

That sure looks like junk science to me. The say passenger cars get 2-3 MPG increase, and they say that's a 4% increase. So they're getting somewhere between 50-75 mpg?! Not many non-hybrid passenger cars can pull that off.

My 4WD
Wife's 4WD

I researched this a while ago... and we had a whole thread on the FEH Yahoo! group about it.

Bottom line is it couldn't hurt, but it's quite doubtful that consumers will see any real benefit. It's tech that's been employed by aerospace, airlines, trucking fleets, race cars, etc. where tolerances are very precise, or where tire deterioration is more of a factor (multiple retreading).

It is slowly seeping into the consumer market though - Costco fills all their new tires with it.

Now, you want something to really screw with your mind and start up a debate . . . ? Research adding acetone to your gasoline.

I see nothing wrong with filling tires with pure nitrogen at the time a tire is installed AT NO ADDITIONAL CHARGE - it can't hurt anything. What I do have a problem with is someone charging $8.00 to "empty" a tire and refill with probably $0.08 worth of N2.

To get pure N2 in a tire you would have to evacuate the tire completely, not just let the air out. 0 PSI on a gauge still means about 14 PSI absolute (1 atmosphere) in the tire. Since most tires are filled to roughly 2.5 atmospheres on the gauge, there would still be a considerable amount of plain old air in the tire.

I doubt highly that tires are (or could be) evacuated so that you had 100% pure nitrogen in the tire.

Is there any impartial scientific data out there on this?

Nitrogen filled tires contain less moisture (if any). That's the key, regular air pumped tires contain a lot of moisture because the pumps do a poor job of removing the water prior to it getting into your tires. Because of this, your car will fluctuate in pressure when driving, so it's not consistent and this is the main reason nitrogen is used in racing, they want a consitent tire pressure that they can measure and work with.

As for improving FE, that's total BS. A properly inflated tire is KEY for FE, what was used to inflate the tire is irrelevant (nitrogen vs air).