DIR Tire Gas?

[D_B]

The only stability comes from the bigger molecule that diffuses slower through the rubber, so your pressure stays optimum for longer and on average you will gain on tire wear and fuel consumption.

Nothing to do with extreme conditions.

... and that would be a good thing because no one it seams, checks air pressure any more ... I see tires all the time that are so low, as to be obvious (how about 12to15psi in tire?) and must be causing all kinds of handling/safety issues .. and the person driving can't tell something is wrong??!!! :11:

 

[Atticus]

... and that would be a good thing because no one it seams, checks air pressure any more ... I see tires all the time that are so low, as to be obvious (how about 12to15psi in tire?) and must be causing all kinds of handling/safety issues .. and the person driving can't tell something is wrong??!!! :11:

I check mine - that's how they got topped off with ean50. :14:

 

[diverrick]

Aircraft have long used Nitrogen in the tires. It is used to help keep the fire danger down, as no oxygen, means no fire. And you would not want to be around when a large aircraft tire goes off!! They also have fuse plugs built into the rims, that'll blow if the pressure gets too high inside, due to heat. Never heard of it giving you better mileage though. It would have to be a very small change at best.

 

[cerich]

I think I have ean50 in my tires right now. Probably not the best idea since the extra oxygen will accelerate their decomposition, but it sure was convenient.

don't feel bad I have mix, 25/17 I believe (not my fav mix but was teaching a NAUI Helitrox course..)

 

[airsix]

The ONLY reason race teams use Nitrogen is because there is less pressure change for a given temperature change than with air. Tire pressure on a race car is critical for optimizing traction (a function of tire temperature and distribution of weight across the tire's contact patch). For example, using air, the tire pressure of my time-trial car after the first lap on a 1.25 mile course can increase by 12psi. That pressure swing would be less if nitrogen were used instead of air. The pressure swing on a street car is much less because you're not heating up the tires with 4-wheel drifts around every corner.

I don't think nitrogen is necessary on a street car because you don't have enough information to set the pressures optimally. Manufacturers test cars for optimum operating pressures and put a little sticker in the door-jam so you know what cold-pressure to inflate to. They assume you are filling with air. If you fill with Nitrogen, but use the recommended AIR cold pressure your operating pressure will likely be BELOW optimum. If you do plan to fill with nitrogen, my recommendation is to first use air & set to your car's cold pressure spec (the car's spec, not the tires spec!). Then go for a nice long drive and measure the hot pressures of each tire. Average the numbers side-to-side so you have average front and average rear. This is your 'hot pressure target' (possibly different front and rear) regardless of what gas you use. Now fill (a little high) with nitrogen and go for a nice long drive to get the temps up. Then measure your hot pressures & bleed them down to your hot pressure targets previously established with air. When the tires have cooled (overnight) you can measure the cold pressure to know your nitrogen cold pressure target. Now you have to deal with the dilema of having a nitrogen source whenever you need to adjust your pressures - because you should be checking them regularly and they will need periodic topping off. And last thing... use a good dial pressure guage, not one of those worthless pencil guages.

All my tires run EAN21. Even my race car. I think the nitrogen thing is silly unless you are running a FIA formula race team.
-Ben M.

 

[cerich]

The ONLY reason race teams use Nitrogen is because there is less pressure change for a given temperature change than with air. Tire pressure on a race car is critical for optimizing traction (a function of tire temperature and distribution of weight across the tire's contact patch). For example, using air, the tire pressure of my time-trial car after the first lap on a 1.25 mile course can increase by 12psi. That pressure swing would be less if nitrogen were used instead of air. The pressure swing on a street car is much less because you're not heating up the tires with 4-wheel drifts around every corner.

I don't think nitrogen is necessary on a street car because you don't have enough information to set the pressures optimally. Manufacturers test cars for optimum operating pressures and put a little sticker in the door-jam so you know what cold-pressure to inflate to. They assume you are filling with air. If you fill with Nitrogen, but use the recommended AIR cold pressure your operating pressure will likely be BELOW optimum. If you do plan to fill with nitrogen, my recommendation is to first use air & set to your car's cold pressure spec (the car's spec, not the tires spec!). Then go for a nice long drive and measure the hot pressures of each tire. Average the numbers side-to-side so you have average front and average rear. This is your 'hot pressure target' (possibly different front and rear) regardless of what gas you use. Now fill (a little high) with nitrogen and go for a nice long drive to get the temps up. Then measure your hot pressures & bleed them down to your hot pressure targets previously established with air. When the tires have cooled (overnight) you can measure the cold pressure to know your nitrogen cold pressure target. Now you have to deal with the dilema of having a nitrogen source whenever you need to adjust your pressures - because you should be checking them regularly and they will need periodic topping off. And last thing... use a good dial pressure guage, not one of those worthless pencil guages.

All my tires run EAN21. Even my race car. I think the nitrogen thing is silly unless you are running a FIA formula race team.
-Ben M.

That was educational, thanks!

 

[Jamdiver]

Even Costco does it. better gas mileage, supposedly. N2 more stable under extreme conditions.

Learn something new ever day..........

 

[The Chairman]

If you have ever examined the anatomy of a blow out, you would see how destructive oxygen can be.

It starts with a slow leak, usually on the RR tire. Probably a nail of some sort has punctured it and it's still in, creating a slow leak.

Because it's a FWD car, you don't notice the extra drag by that tire. The power steering compensates nicely as the pressure slowly drops over a week or more.

Inflated the rear tires probably have 28 psi (almost 2 bar), but the slow leak has reduced this to a mere 15 psi (1 bar) so now it has 2 atmospheres of pressure in the tire.

Now unlike it's biased counterpart, the sidewalls in radial tires have NO ability to support your car (unless you have run flats). That's why there is always a slight bulge on the bottom side of the tire. Remove half the pressure of that tire, and the bulge becomes a pronounced bend. on either side. Now consider that during every rotation, the entire sidewall flexes. Small bulge=small flex. Large bulge (bend)= large deflection. This will generate considerable heat as the rubber and cords flex from flat to bent. Now add the added PPO2 (from 0.21 to 0.42 ata) and you start the hot rubber INSIDE the tire to combust.

Don't believe me? Look inside of a blow out and it looks like someone got happy with an acetylene torch in there. Using N2 exclusively would eliminate many blow outs, though not all.

For your safety, NEVER EVER inflate a tire that has been run almost flat: ESPECIALLY if it is hot to the touch. Use a cage or a remote inflator and stand OUT OF THE WAY. Never have a tire repaired that is discolored on the inside, with a hole in the sidewall or if it has been rim cut. Check your tire pressures weekly or invest in a run flat monitor.

 

[Diver Dennis]

Very interesting. They were talking about this on CNN today. I doubt whether the gas stations around here would have it though.

 

[Mad Scientist]

Ok here is what I know about N2 in your tires. It is a complete waste of time and resources, here is why....

Argument #1 For N2, the oxygen molecules are smaller and difuse out of the tire faster than N2 will.

Ok this is true, O2 is smaller than N2. However the differnece is about 2% and on an atomic scale that is not going to make a difference. If by chance this does make a difference then everytime your tire is low the O2 will have diffused out and the N2 will stay behind, a few "top offs" of the pressure in the tire will leave a minute amount of O2 and the tire will now be filled with N2 anyway.

Argument #2 N2 stays cooler longer giving more constant air pressure (ie better gas mileage).

Wrong, all tires heat up due to friction (the force that keeps us on the road and moving forward ie. traction), not what gas is in them, a tire at 33 psi has about 6 psi O2 in it not enough to make a difference. In the temperature range we are talking about N2 and O2 behave very much the same in terms of thermal expansion.

Argument #3 Nitrogen is not flamable/not reactive

Ok another true statement, but how many times have you seen a car run down the road with the tires on fire? Really I am serious here, have you? The inside of the tire may be free of O2 and not able to catch fire but what about the outside it is still in good ol' air. This is the same argument that O2 rots the tires from the inside out and N2 is better for this reason. Well if the air outside is ok why should air inside be bad.

Argument #4 Compressed N2 is dry.

This I wont argue against N2 is dryed (some times, but most of the time not well). But dry air (like from our SCUBA tanks) would provide the same protection.

IMHO Nitrogen in your tires is not worth the money they charge for the service.