I've also seen that happen. Tires randomly stop leaking after nothing but just topping up.
I'm Considering Nitrogen vs Air Again
- Thread starter Mr_Luke
- Start date
I expect there would be no measurable difference in the rate of diffusion between air and "pure" nitrogen through a tire wall or a tire valve stem.
Paying for Nitrogen is a waste of money. But there's no harm in using it - except to your wallet.
I suspect it is really a way to convert the cost of generating dry compressed air (supplying and maintaining a compressor) into a profit center. If you pass on the expensive nitrogen fill at a tire shop, what do you suppose they would do? I expect they'd fill your tires with nitrogen (simply because they no longer have a compressor).
Paying for Nitrogen is a waste of money. But there's no harm in using it - except to your wallet.
I suspect it is really a way to convert the cost of generating dry compressed air (supplying and maintaining a compressor) into a profit center. If you pass on the expensive nitrogen fill at a tire shop, what do you suppose they would do? I expect they'd fill your tires with nitrogen (simply because they no longer have a compressor).
I've owned a nitrogen generator for 15 years now, and have inflated thousands of tires that I install with it for free. If someone wants to put nitrogen in their tires I charge like $12 for it, and which isn't enough even if I was using plain old air because it takes time to deflate, purge, and fill. It might not make a huge difference, but it needs to be maintained just like air. It does leak out slower, but the biggest difference over time I've noticed is the wheel bead seats, and valve stem corrosion is much less. I'm still running 16 year old Camry aluminum wheels in the winter that have been on 4 different cars and they still look good on the inside. The tires shouldn't degrade as fast either with less oxygen permeating through the rubber. It is the excess moisture, and oxygen that constantly gets put in the tire using compressed air that makes the biggest difference. The O2 level in the tire will equalize out to 5% over time using N2, and the moisture level also changes, but you are not adding to the problem topping off with wet air and O2 constantly. Oxygen is pretty powerful stuff when you think about how we need it just to stay alive.
So...is the improvement you saw in corrosion from the removal of O2?
Or the removal of water?
The benefit of N2 for passenger cars is that it is dry. If you were using wet shop air before, then, honestly, you weren’t doing your customer’s tires, or your own tools, any favors.
I drain my compressor in the morning, before I start work, and then at the end of the day, when I’m done. If it’s seeing heavy use, I drain during work. A 1/4 turn ball valve makes this easy.
If I ran a commercial shop, not just a hobby shop, I would get an in line drier, for both my tools, and my tires.
Or the removal of water?
The benefit of N2 for passenger cars is that it is dry. If you were using wet shop air before, then, honestly, you weren’t doing your customer’s tires, or your own tools, any favors.
I drain my compressor in the morning, before I start work, and then at the end of the day, when I’m done. If it’s seeing heavy use, I drain during work. A 1/4 turn ball valve makes this easy.
If I ran a commercial shop, not just a hobby shop, I would get an in line drier, for both my tools, and my tires.
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And they would just give you the black valve caps instead of green.
An absolutely ridiculous one I've seen with the nitrogen fill is a new car dealer, putting stickers on their car claiming the tires are nitrogen filled, and adding an extra $100 or so to the price of the vehicle. So, you're telling me they purged all the air out of the factory tires, and refilled them with nitrogen? Sure...
Nitrogen is a waste of money if your paying for it as a consumer for tires. If they do it free, sure, try it out, but don't waste any money on it fwiw...
First, thank you thank you for spelling "lose" correctly!
So many voice recognition or spelling failures between "loose" and "lose". Native English speakers should know the difference. /Rant
That said, unless you frequently have huge temperature swings of 45-50°F, or large changes in elevation, nitrogen's juice is not really worth the squeeze. Unless of course you can get it free or close to it.
Another myth!
Sorry, but both Nitrogen and Air behave the same here. So do pretty much all gases at the temperatures and pressures humans deal with. It's called the Ideal Gas Law (PV = nRT). The only time this isn't so is if you have a puddle of water in the tire - and this would be a HUGE problem if this occurred frequently. (It is extremely rare!)
You seem more knowledgeable on this so not trying to pick a fight but I always thought commercial aircraft use pure nitrogen because it behaves differently with massive ambient temp and pressure swings. Is that not the case? or this that only the case with pure nitrogen that airliners and F1 teams seem to use.
Transport category aircraft are required to comply with AD 87-08-09. Other countries have similar airworthiness directives.
Here is the background from the federal register:
"SUMMARY: This amendment to the Federal Aviation Regulations (FAR) requires that an inert gas, such as nitrogen, be used in lieu of air, for inflation of tires on certain transport category airplanes. This action is prompted by at least three cases in which the oxygen in air-filled tires combined with volatile gases given off by a severely overheated tire and exploded upon reaching auto-ignition temperature. The use of an inert gas for tire inflation will eliminate the possibility of a tire explosion."
CFR Final Rule
You are talking about -70C +30C (or more) temperature difference in minutes (landing descent) followed by abuse during the landing.
I bet temperature inside the tire jumps from -50C (wild guess) to +200C (another even wilder guess) and high pressure in fraction of seconds.
Not even F1 car tire experiences such abuse.
Krzys
I bet temperature inside the tire jumps from -50C (wild guess) to +200C (another even wilder guess) and high pressure in fraction of seconds.
Not even F1 car tire experiences such abuse.
Krzys
But as CapriRacer correctly points out, pressure changes are independent of the gas mixture.
Commercial aircraft tires are inflated to over 200 psi. I suspect that one of the hidden reasons commercial aircraft use nitrogen is because it comes in 2000 psi bottles. I imagine that maintaining a high pressure air supply is way too expensive (and a major hassle!) compared to buying nitrogen bottles.
I think the same thing applies to car racing. The bottles also power the air guns, so they are already there.
I sort of think this is one of those things were the stars align and the moon is in the seventh house (Hair reference!)
Where is the Chemistry here?...air vs nitrogen vs tire leaking. Sounds more like molecular physics to me.
My understanding is that it is legally required for any aircraft over 75tons to use nitrogen or another inert gas due to the risk of autoignition with normal oxygen. My CFI has told me that that nitrogen always has has the benefit of being relatively stable with massive temperature swings and pressure differences in flight I’m pretty sure I heard this in an Airbus documentary from a company spokesperson (I will try to find the link) as well. Would pure Nitrogen not have this benefit? I know that the stuff used in tire shops is not the same stuff used in aerospace applications.
Your CFI is wrong.
Straight up.
Needs to brush up on his basic science if he wants to get an ATP someday.
Nitrogen follows the ideal gas law. If it did not, then the 78% Nitrogen mixture known as AIR would not follow it either, right?
Nitrogen is used in commercial aircraft due to flammability concerns when a tire gets heated to hundreds of degrees.
The temperature swings are true, -70C to +250C. Normal temps. Day in and day out. The pressure during those temp changes follows the ideal gas law.
The tires are 28 or 32 ply rated, and handle tremendous load and speeds. They’re rated for 205 KTS, or about 235 MPH. On landing, they go from zero rotation to 150+ MPH nearly instantly, with a bit of rudder skidding off as they accelerate.
Did you see my response as to the reason?
Having two air compressors in my garage, I see no value in filling tires with nitrogen. I'm sorry to say I don't buy into the hype for a passenger car.
