For those of you that have trouble remembering to check tire pressure, there is some new technology being used in the last few years. Try calling around and find a tire shop that uses nitrogen instead of just air to fill the tires. This will be easier to maintain because nitrogen molecules are larger than than just plain air and will not leak out of your tires. Another good thing about using nitrogen is that it doesn't react to hot or cold so your tire pressures will stay accurate. In my area there is a place called Costco, which is a bulk retailer and they also sell tires. They use nitrogen exclusively and the cost is about $5 per tire to have yours done. Hope this helps.
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It's a load of bull...
This story about nitrogen molecules being smaller and not leaking out as fast as air a big load of BS.
What IS air?
Air is 78 percent nitrogen by mass!
Oxygen accounts for about 20 percent and the remaining consituents are other gases including water vapor. ("Vapor" is the same thing as "gas" - one of the three normal states of matter, the others being liquid and solid.)
The problem with using air is condensation of water vapor if the temperature of the tire drops below the dew point of its contained air. Condensation can drop air pressure - but usually only slightly - and the liquid water drops can cause corrosion of the wheel interior including the bead sealing surface. Even without condensation the pressure of a tire will vary about one psi for every 10 degrees F change in temperature.
Commercial nitrogen is very dry, but that doesn't mean compressed air will cause condensation if you take reasonable precaution.
The important thing is to ensure that the air supply is as dry as possible. Most commercial compressed air systems have dryers, and you can buy one for your home compressor, and check your tires and fill your compressor on days when relative humidity is low if possible.
This weekend we are having a "Santa Ana" condition in Southern California - warm very dry air blowing in off the desert from the east. That means it's time to fill the compressor and air all the tires.
Duke -
Re: Tire pressure question
Saw green valve stem caps on a co-workers car and commented on the color 6-9 months ago. Found out they were placed on the valve stem after the tires were filled with nitrogen to identify the tires filled with nitrogen. Don't see to many cars with the green valve stem caps. The co-worker got nitrogen when new tires were bought.Comment
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Re: It's a load of bull...
Nitrogen In Tires
Duke, what is the other 22%?
Here is something off the internet:
Here are a few other benefits of using Nitrogen in tires:
[1] Nitrogen is denser than Oxygen: This means the larger molecules escape less easily from tires resulting in a more gradual loss of pressure over time. According to the Michelin Tire Manual, a tire that is inflated with Nitrogen loses its pressure 3 times slower than if it were inflated with air.
[2] Nitrogen is moisture free: Pure Nitrogen inflated tires experience less steel belt and rubber degradation. Nitrogen use also reduces valve and wheel corrosion.
[3] Nitrogen provides longer tire life: Nitrogen inflated tire run cooler and require less maintenance according to the Goodyear application bulletin.
[4] Nitrogen is non-flammable: Nitrogen technology has been used in aircraft, military and race car technology for over thirty years.
Believe what you will.Comment
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Re: Tire pressure question
It's being marketed now by almost all the tire shops as a "miracle" that will increase fuel economy (at $5.00 per tire, of course); has zero impact on fuel economy if you use ordinary air, check your tire pressure occasionally, and maintain your tires at the proper inflation pressure.
"Marketing, son, marketing - that's where the money is."Comment
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Re: Tire pressure question
Unless the shop installing the nitrogen evacuates the tires (I'm not sure how they will do that with the beads seated, unless they have a vacuum chamber) there will be whatever the volume of the tire is of air before they start filling with nitrogen. Thus 20% or so of the quantity of the material in the tire will be something other than nitrogen regardless of what they do. I'm sure my numbers are an over simplification. I'll leave the sophisticated engineering types to do more refined calculations. I just wanted to make the point that regardless of what one does, the fill will not be pure nitrogen, unless one goes to extreme lengths.
All that said, aircraft tires are normally filled with nitrogen -- but they reach altitudes, and are subject to speeds and landing forces which generally exceed anything our cars are likely to encounter.
If someone thinks nitrogen is worth $25 per vehicle, be happy. I'm sticking with ordinary atmospheric air, with all its pollutants, even in my 36-year old original tires. Each of us can make their own choice. It IS nice to have choices.TerryComment
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Re: It's a load of bull...
John
The "...other 22%..." is oxygen with about 1% argon.
Nitrogen (gaseous, 1.185 kg/m^3 at 59F) is NOT denser than oxygen (gaseous, 1.354 kg/m^3 at 59F).
Nitrogen (atomic #7) IS, however, larger in both atomic and molecular radius than oxygen (atomic #8) in the same state.
The non-flammable claim also applies to "air", and also to oxygen. Oxygen supports combustion, but is not combustible.
'Google engineering' has its pitfalls, since the marketing hype is often difficult to distinguish from real science.Comment
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Re: Tire pressure question
Terry, if you have 36 year old tires you can't be driving on them much and you have worse problems than tire pressure. lol
The basic reason I mentioned nitrogen is it does not react to temperatures, so if you are not the type of person to keep an eye on your tires and the weather, you will get better milage with nitrogen. Of course if you are diligent and keep your tires perfectly inflated you will get the same results with plain air, however most people don't. :-)Comment
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Re: Tire pressure question
If you are suggesting that nitrogen has a smaller chance at escaping a tire due to the very slightly larger molecular diameter, you are right.
If you are suggesting that nitrogen will not chemically react as readily as oxygen, you are also correct. But what (short of a rusty rim) would oxygen react with anyway inside a tire at normal temperatures.
But if you are supposing that nitrogen does not "reacts" to temperature by changing internal pressure as readily as oxygen, then you are dead wrong. An ideal gas (the way that both oxygen and nitrogen react at normal temperatures) would react to the following formula: PV=nRT where P is pressure, V is volume, T is temperature, n is the number of molecules, and R is a constant. This formula works the same for ALL atmospheric gases and shows that as temperature increases, so does pressure. In this way, nitrogen is no different than oxygen.
Just a quick note, if anything, because of its larger molecular diameter, nitrogen is likely to "change" MORE than oxygen (and by change I mean its effect on pressure) becauese oyygen is closer to the "volumeless" molecular diameter of an ideal gas. But at typical atmospheric temperature, this difference is negligeable.1967 L71 Silver/Black Coupe - Unrestored/Original Paint, Top Flight at 1998 Regional in Ontario, not judged since
1995 Red/Red ZR-1 - Top Flight back in 2010 Michigan Chapter meetComment
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Re: Tire pressure question
Yes John, I have 36-year old tires on my 36-year old Corvette -- and you are right, I don't drive very much on them. I don't have any problems though, including tire pressure or deductions for tires in judging.TerryComment
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Re: It's a load of bull...
Duke....I always believed the reason the NASCAR boys used Nitrogen in their tires was because it doesn't expand like plain air. True????Comment
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we used nitrogen in race car tires to prevent
air pressure build up caused by the moisture inside the tire raising the tire pressure as they heated up. we also have used "bleeders" on the valve stems that allow the air to escape as the pressure built up. NASCAR does not allow "bleeders" so nitrogen is used BUT the pressure still builds up,not as much as with compressed air,so the sharp guys in NASCAR "drilled" or lasered very small holes in their rims to let the extra pressure out durring a run between tire changes. NASCAR did not like this creative engineering so it was "outlawed"Comment
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Re: It's a load of bull...
I think it is because the NASCAR boys have nitrogen bottles readily available to run their air wrenches. Why not use it for the tires. If I was in the tire business and could sell nitrogen at $5 per tire, I would do that too. I have a tire off of my 31 cadi. that was on the car in 1941. It still has a little air and its a tube type. Frankly I am not too worried about leakage, I have a ready supply of air.Comment
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Re: It's a load of bull...
No. As stated in another post both air and nitrogen behave as ideal gases and follow Boyle's Law, including air with water vapor content. The issue is water vapor condensation, so if your air supply is dry and the tire temperatures don't drop below the dew point of the contained air, it's not an issue.
Someone brought up another good point. Unless you evacuate the tire, the air inside the tire stays there after filling to pressure with nitrogen. At 30 psi the original air makes up about one-third of the gas in the tire, so the concentration of oxygen and water vapor is about one-third of what it was before the pressure was increased. This drops the dew point, which is good, but dry air has the same effect.
DukeComment
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Re: we used nitrogen in race car tires to prevent
Unless the air supply is so wet that liquid water is injected into the tire along with the air, there will be no additional pressure buildup due to water vapor. Like any other gas, water vapor behaves as an ideal gas and expands (or builds pressure if volume is constant) as temperature increases.
Poorly maintained compressed air systems can have excess water. Ever opened the valve on an air hose and seen tiny water droplets in the stream?
DukeComment
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