Nitrogen in tires?

[Rob S.]

From the service manual:

"H-D does not perform any testing with only nitrogen in tires. H-D neither recommends nor discourages the use of pure nitrogen to inflate tires."

To me, that's darn close to an endorsement. What are the benefits? Saving a few ounces of unsprung weight?

[Nessism]

I did a google search on this topic and found a bazillion links such as these one...

http://www.popularmechanics.com/cars/how-to/a3894/4302788/

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=191

[JJ]

Just a way for tire dealers to make a few extra bucks per customer. No real benefits.

[Steve]

I use a proprietary blend of 78.09% Nitrogen.

Although "proprietary", it's actually rather easy to find.

.

[Griffin]

Here's the deal with using nitrogen in tires. I know this, it's part of my industry.

The nitrogen that tire shops use comes from a good old air compressor like many of us have in our shops. The difference in the system they have compared to what we have is that the air coming out of the tank under the compressor passes through two stages of oil removal filters, then through a desiccant dryer that removes enough moisture from it to lower its pressure dewpoint to approximately -40^o F. That means that no condensate will drop out of the air unless it is cooled to below that temperature.

The now dry, oil-free air (<0.001 ppm oil concentration) then passes through what is called a nitrogen generator. This term is a bit of a misnomer. It should actually be called a nitrogen separator. This is a device filled with a mixture of molecular sieve desiccant and activated carbon. The oxygen molecules in the air adhere to the carbon particles, allowing the nitrogen, argon, and other trace gases to pass downstream to the nitrogen storage tank. It is a fairly impure gas, being about 99.2% purity (industrial nitrogen generators can produce nitrogen purities down to 99.999% purity if necessary for a process).

The oxygen molecules are eventually vented to atmosphere, which is why it is important not to locate a nitrogen generator in an enclosed space where there could be open flames.

Now then, using nitrogen generated thusly is better for your tires than using compressed air straight out of your compressor. Not because the oxygen is gone, but rather because the water is gone. The air coming out of a compressor is essentially saturated, and once it goes into your tires, the water condenses out and you have slightly acidic water coating the inside of your tires.

So why bother separating the oxygen and just go with a desiccant dryer?

Marketing.

Saying "pure nitrogen" is a much easier concept for people to grasp than saying "-40^o F dewpoint dry air". Nitrogen is obviously different than air (although most people probably couldn't tell you why), whereas dewpoint...-40 temperature...wha...what????? Won't air that cold ice up my tires?

So it's a marketing gimmick that does help maintain more consistent tire pressure and probably does help a bit with rolling resistance and maintaining cooler operating temps. That might mean the difference between 1st and 2nd at Daytona, but probably won't do a damn thing for people commuting to work.

[Cipher]

about 22% of my tire has no nitrogen in it.
It is a scan like a tranny flush.

[mmattockx]

Here's the deal with using nitrogen in tires. I know this, it's part of my industry.

<snip>

So it's a marketing gimmick that does help maintain more consistent tire pressure and probably does help a bit with rolling resistance and maintaining cooler operating temps. That might mean the difference between 1st and 2nd at Daytona, but probably won't do a damn thing for people commuting to work.

Good explanation. Just for more clarity, the use of nitrogen in cars/motorcycles started in formula 1 and motoGP. There it provides more consistent tire pressures (again, due to being extremely dry) and leaks a bit more slowly through the tire membrane because of the size of the N2 molecule. Those guys can actually feel the difference on small pressure changes and were looking for the ultimate in consistency so they went there. For the rest of us it is nothing more than a gimmick that some shops try to make $$ off of. My truck came from GMC with nitrogen in the tires. On the first flat repair I had done the shop guy was horrified that I didn't care if they used air or nitrogen to refill it. It was good for a laugh, at least...


Mark

[Steve]

When I get new tires on my van, the shop only uses Nitrogen to fill the tires, and they don't charge extra for it. My problem with that is that they install those silly GREEN valve caps to show that they used Nitrogen. Before I leave, I take off all the green caps, carry them back into the store and ask to have my old valve caps back or my next set of tires would be from the shop in the next block. They only hesitated once, then realized that I meant business. I also check when I have the tires rotated and balanced, to make sure some new recruit didn't put green caps on out of habit.

.

[Griffin]

The EPA gave out tax breaks and direct monetary incentives to automotive shops to financially assist in purchasing N₂ generators. They rationalized it by saying it "helped reduce greenhouse gases."

As with pretty much all "green" industries, it's a scam to dole out government funds to individuals and companies.


Follow the money......

[geol]

I think one of the main reasons for the Nitrogen in tires is that water is less and there are those tire pressure sensors in many car tires these days. I was told they rust if you keep filling with regular air from a compressor. If you want green caps, buy some Slime as they give you green valve stem caps so someone will know the tires have been "slimed". I don't think you can use Slime in bike tires as the speed of a tire is limited pretty severely using this glop.

[jsandidge]

With my bike the PO had slimed the tires to try to get them to hold pressure before I bought it. It had been sitting for 14 years. The slime didn't help, and it sure was a mess to get cleaned up when I mounted the new tires.

I was told by the Nissan dealer when I bought my 09 Rogue the same thing about the tire pressure sensors. Actually, they told me about it when they replaced them because of a recall.

[Griffin]

I don't buy it with the sensors.

They've been installed in cars for about a decade now, and I would guess most of them are operating in at least partially contaminated nitrogen, if not 100% gas station/home garage produced saturated compressed air. I know my tires pretty much run that way.

I've never personally had a failure, and I've not heard of any mass failures of them either.

[geol]

Don't really know if it is true that the sensors can rust. This is what I was told by my Ford dealer who forced me to buy nitrogen when I bought my 2013 truck. Actually they install it in all the new vehicles with TPS and that was the reason I was given. They would not consider taking their nitrogen back and filling with air as I told them that would make me happy as I didn't want to spend the money for nitrogen knowing I would end up topping off and filling the tires with air from my compressor.

Interesting article on nitrogen in car tires:

http://www.edmunds.com/car-care/should-you-fill-your-cars-tires-with-nitrogen.html

[Doug]

Nitrogen is a sales gimmick

The idea come from aircraft tires. There is very little similarity between car tires and most aircraft tires... yes your right, they both roll.

Fighter tires are filled with nitrogen to about 400 PSI for a couple of reasons. The pressure remains more constant given radical temperature changes the tires see in a short period of time. Sea level to 60,000 feet in a few of minutes and back to sea level.

You don't want a blow out landing on a carrier and miss the trap. You won't be able to go around.

The other concern is, Oxygen is an oxidizer, it can influence internal tire degradation. N2 eliminates that concern as there is no practical method of determining the occurrence or severity of oxidation in the tire - the key word is practical.

Tires that are filled with nitrogen are done so in a purge cabinet. That's a chamber the mounted but not sealed tire and wheel are placed, the chamber sealed and the air evacuated from the chamber. The chamber then filled with Nitrogen, the tire sealed to the wheel and then the tire final pressure established.

The chambers are designed to contain a tire explosion. Take a look at the number tires on an Air Bus A380 and the weight of the aircraft.

You won't get this at Big Zero Tires.

Not to give away Steve's preprioritory blend secret but air is already over 78% Nitrogen.

[rapidray]

We use nitrogen on the rear slicks on drag bikes to keep the pressure stable. Burnouts will raise the tire pressure due to heating the tire, that won't happen with nitrogen, or very little if it does. Been doing it this way since the 80s.
Ray.