Air vs. Nitrogen

[tireman9]

What effect does the constant changing pressure in the tires play on longevity.

Any material that is constantly being stretched and then restored to normal is going to take a hit.

True but that is what Tire Design is all about. Making a product that will function in its intended use for a reasonable time.

The steel belts will eventually suffer fatigue and fail.

Belt edge fatigue is much more a result of over deflection due to under-inflation and/or overload than due to normal pressure changes due to normal operation.

Tires with atmospheric gas constantly change pressure as they get warmer/hotter.

If the iinflation gas is dry the amount of expansion is is about the same for all the common gases at ordinary temperatures. See Charles's law.

The key word is "dry".

The whole selling point of Nitrogen is the lack of pressure change / molecular size and shedding of heat.

According to THIS site the thermal conductivity of 100% Nitrogen is 0.015 vs air (78%N2 & 20% O2) at 0.015, so how is the heat transfered faster with 97% N2 inflation gas in your tires?

Drive your motor home for ten miles on atmospheric gas and then take a laser / infared reading and then drive it for ten miles on 100 % Nitrogen and compare readings. The degree of accuracy has been covered HERE and HERE and has been demonstrated is not sufficiently accurate to measure the theoretical temperature difference due to 10 psi change.

Propane is an excellent gas for filling tires, it sheds temperature (refrigerant) amazingly well. I have used it when I was in a pinch to inflate tires out in the boonies. One 20 lb bottle (bbq size) will fill about twenty tires because it is a compressible gas. It is in liquid form in the bottle and converts to gas as it is released. The only problem is that it does expand like air,, and of course the false fear that it will explode.

All refrigeration units around the world (except USA) are now filled with propane (hydrocarbon gas). Freon has gone by-by. Sorry DuPont.

Propane has a very small window of opportunity to explode. Too pure,, no boom,, to weak,,no boom. Put your hands on a tire filled with propane vs air and you will be amazed. You can keep your hand on the propane tire but not on the aired up tire.

So you are saying propane gas will not explode or have a negative effect on the rubber?

So there are other options than atmospheric gas. Agree, it's just that there is a cost and I can't find the benefit that sufficiently offsets the cost.

By the way, I have transported hundreds of Mobile Homes (70's) with propane filled tires, greatly reduced blow outs,, no fire, just large noise.

And NO.......I'm not on drugs...........

Wally, Did you read my post on Nitrogen? The science and chemistry are covered in detail there.

I guess we will just have to agree to disagree.

Wally C.

Wallace I. Crawford

96 Dolphin 36' 454

Recently traded for 2005 Monaco Knight

38' 4 Slides 330 Cummins

@ LaMesa RV -Sanford Fl

[tireman9]

Tireman, maybe I missed it, but did you ever get a chance to research a good replacement for the air dryer you had originally recommended, which later seemed to drop off of Harbor Frieght. I only saw one that had poor reviews.

Check out this post. The dryer or similar, is available at most auto parts stores and home centers. Go to their web site and search on DESICANT and you will see who hav the dryer and the psi rating.

[tireman9]

Stuart,

Interesting posts by everyone. BretT is correct, pressure is controlled by Boyles Law. The pressure change associated with a 40 degree F temperature change is calculated to be approximately 7.286 psi offset from a 100 psi baseline. Although I have not calculated the delta between 100% nitrogen vs 100% air, it is probably less than 1 psi different from the number calculated above. Not a significant change to get excited about. We have migrated our truck fleet where I work to running 100% nitrogen. Tires are claimed to run cooler, last longer, and get a 1-3% improvement in gas mileage (or at least that is the claims being made). One of the down sides is that the benefits disappear if you contaminate the tires with air, once filled with 100% nitrogen.

Moisture and oxygen are both factors that are detrimental to tire life. Running 100% dry nitrogen may be the best choice in providing a marginal benefit, but one must weigh those benefits noted above with the headaches of always finding a source of 100% dry nitrogen to fill your tires with. The next best option that many have touched on is to use a reliable source of dry compressed air. If you are running close to the limits of the tires, may be an option worth considering.

The benefits of running nitrogen are there, but are probably not significant in the having a noticeable impact on gas saving or decisions of when to change to the tires out due to age for most RV'ers.

Happy RVing.

Terry Zimmerman, P.E,

Terry, as a PE maybe you can jump in.

If we assume that a tire containing 95 - 98% N2 will have less pressure increase due to a temperature increase because the inflation gas is dryer, how do we get better fuel economy?

Are the sellers of the N2 also claiming that lower tire pressure improves fuel economy? maybe we should all run out and lower our inflation to zero and everyone would get 200 mpg. Not.

[n9938u]

I have been using 78% nitrogen for years. It works well, is readily available, and usually is free.

[tzimmermn]

Stuart,

Your credential indicate you are have a a lot of experience in this area and I would rely on your experience as my guide regarding this discussion. My only point was that the differences are minimal at best and probably not something to get terribly excited about. I have no position on claimed results from vendors, although it stands to reason that the elimination of oxygen and moisture should provide some benefits in tires longivity.....how much, I don't know.

We have only recently changed over to running the nitrogen in the tires in the fleet of trucks we service by an organization we support, and so the verdict is still out regarding realized benefits. This is not my primary area of expertise, so I am still waiting for some feedback on actual documented results that can be validated.

[QuiGonJohn]

Tireman, can you give me the NAPA part number off that? I have looked in Home Depot, Walmart, Bennett Auto Supply and Advance Auto Supply and so far cannot find this, or anything really similar. I found one filter at Advance that says it removes small water particles, but nothing about dessicant. I see a patent number but not a part number, maybe that is on the other side.

[tireman9]

NAPA NTH 907292

WW Grainger 6ZC63

Harbor freight 68215

SEARS SPM1189759601

Home Depot Model # 50238

Advance Auto & AutoZone do not carry this level of shop tool.

Be sure to check the max air pressure rating before you buy for your tires.

[QuiGonJohn]

Picked up a pair at local NAPA, $16.29 with tax, for the pair.

[N2TYRZ]

Nitrogen if overcharged or not offered free with new set of tires, then Nitrogen inflation could be seen as a scam. I respect all the science that many come to blogs to debunk the merit of nitrogen but I have installed nitrogen in hundreds of tires with satisfied users in many applications.

Most tire and car manufacturers have tested and approve the use of nitrogen. Many local tire shops down play the benefits they, first don’t want to invest in a machine and want/need to sell tires. Michelin factory in Greenville, SC offers nitrogen inflation station for their employees.

Costco offers nitrogen free when you purchase tires. Do you think they would invest 8-10k per machine at over 400+ tire locations if it didn’t have some merit? Costco self insures their tires and majority of people don’t check psi or rotate as recommended so they have found better performance less failures with nitrogen. Costco sells millions of tires per year.

Jay Leno uses in his entire car collection, Google and watch the video.

Lance Armstrong and other tour De France riders use Nitrogen. A bicycle tire with what little volume it has why would they go to the trouble if not for the benefits.

Nissan GTR is shipped from factory with Nitrogen. Volvo has inflated all their spare tires with nitrogen for years. Most spare tires I have checked are severally underinflated never checked a Volvo yet though.

My opinion and experience using Nitrogen has been positive. Yes regular air would do but I opt for the better inflation media. Nitrogen inflation is obviously not for everybody.

I do a part time business a car cruises for over 5 years with positive feedback on better psi retention, handling improvement etc. Some have gone over 2 years with no psi loss where they would need to top off using air. I charge $20.00 for 4 tires and many times let customers try before they pay. I haven’t lost a sale yet due to Nitrogen not delivering enhanced performance.

One of My best experiences is an independent trucker owner operator. He and his wife are a team that travel 5k every week long haul. Using same brand of tires they average 300 to 330k on driver tires. I put in nitrogen in a new set they got 475k. During that time he did not need to add any nitrogen or rotate tires as he did using air. The tire shop said he could sell the 475k tires to a local trucker and still had some life. I put in my neighbors riding lawnmower where he after winter had to air up tire and during use several times but now once a year with nitrogen.

Wal-Mart has tested and converting their fleet to nitrogen. Many other trucking companies’ have done side by side test and have experienced better tire life, less failures and small mpg increase over air.

Nitrogen out performs air whether in an airplane (federally mandated for safety), racecar, military vehicles, motorbike, truck or bicycle tire. Nitrogen inflation will the standard in the future and should be offered free hopefully.

An option is to buy your own tank and regulator go in with a few friends and have filled at local welding supply company that delivers 99.999% nitrogen. Purge your tires twice down to about 5# on car tires 10# on truck tires so not to break the bead or hurt sidewall and top to recommended psi stated on vehicle manufacturers placard not max psi on tire which usually is 20-30% more and your done. Do the spare too I usually add extra 5# so when needed its ready to go.

[BoondockSaint]

It's a fallacy. Nitrogen doesn't do anything that compressed air won't.

[N2TYRZ]

What are the won’t in a little detail ?

[RVerOnTheMove]

N2TYRZ...i.e. Nitrogen Tires

First, welcome to the forum!

We are always glad to have differing opinions jump into the fray.

Now, since air is already 78% N2, could you provide us with some kind of scientific evidence that N2 actually provides any major benefits compared to "dry" atmospheric air other than not having to put some air in your tires once or twice a year?

The "he said, she said" stuff does not count.

[N2TYRZ]

RVerOn TheMove,

Thanks for the invite on this subject.

Proper tire psi is paramount whether using air or high purity nitrogen.

Introducing N2 at a level from 78% to 95% tests have shown with reduced moisture at the same PSI cold, He said and She said have noticed an improvement with better pressure retention and handling performance.

Do you have someone you trust that can side by side matched psi for psi with at least 95% Nitrogen in tires whether it be a bike or a car and get their feedback?

If any of you live in the Portland, Or metro area I will do for free or can find another N2 person that may do for free as well.

Im not selling $10,000 N2 generators just an idea for better inflation media that I and many have experienced.

Is synthetic oil better than regular, Is bottled water better than tap, Is Starbucks better than Folgers?

There are many scientific studies beyond me and most of us that prove N2 is better than compressed air.

Its your choice, use which ever you believe will satisfy your needs.

tireman9 input for his wisdom and experience and seems to be an honest guy

If your tires were filled with Nitrogen you can top them off with air as needed. If you want to pay for going from 79% Nitrogen to 95% Nitrogen it is your money.

[RVerOnTheMove]

Is synthetic oil better than regular? Not necessarily.

Is bottled water better than tap? Not necessarily.

Is Starbucks better than Folgers? A matter of choice, not performance.

The reality is that "in an RV" (the reason we are all here) you will not notice a bit of difference between N2 air and atmospheric DRY air in the tires any more than your engine will be able to tell the difference between regular or synthetic oils.

[N2TYRZ]

Good to hear from you again RVERONTHEMOVE. Pursuant to your last rebuttal

Is synthetic oil better than regular? Not necessarily. Agree, but OE recommends for performance vehicles and others.

Is bottled water better than tap? Not necessarily. Depending with chlorine level in tap (some higher than swimming pools) vs none with bottled.

Is Starbucks better than Folgers? A matter of choice, not performance. Agree drink maybe 2 cups a day not a connoissuer .

The reality is that "in an RV" (the reason we are all here) you will not notice a bit of difference between N2 air and atmospheric DRY air in the tires. Disagree better psi retention on the low end of 2 to 1 claims of 3 or 4 times better, and more benefits as per pdf attached files. My neighbor retired with a fleet of 50+ trucks a hundred year old company noticed better tracking down the road in his 38’ RV. And also in his daily driver.

Your engine will not be able to tell the difference between regular or synthetic oils. Maybe so, a dyno test or engine life could be the jury.

Since personal experiences are not relevant here are a few links.

www.tc.gc.ca/media/documents/programs/drexan_1.pdf

www.getnitrogen.org/pdf/FordBaldwinResearchRaper.pdf

www.getnitrogen.org/savebillions/files/Milestone.pdf

Once again, this is my experience and hundreds of customers with satisfaction using N2 over compressed air. It seems not to pencil out on the chalkboard with some critics.

If using good old compressed air or N2 check your PSI before you set out on a long drive at cold recommend pressure.

The Beatles were told “The days of a 4 piece band was over”. What does that have to do tire PSI in RVs??

[RVerOnTheMove]

2 reports from long haul trucking which I dismiss as not being applicable to RVer who usually have to replace tires due to age and not mileage. The middle report about car tires is very interesting but again likely applies more to the age of the tires and not tread wear or safety or fuel mileage.

We will just have to agree to disagree. I will even agree with you that filling with N2 might have some advantage over air since it is guaranteed to be dryer than just about any other choice. Armed with that information I don't believe the costs to setup my 8 tires and the limited sources available to refill as necessary make N2 a practical option.

[N2TYRZ]

I agree at this point in time its a new concept and availability is scarce and cost is an issue. Hopefully will be the norm of inflation in future for free and not an upsell. Anyway good conversation and happy traveling to you RVerOnTheMove.

[RVerOnTheMove]

Standard and free? I'm in!

[tireman9]

I still have to wonder about the claim of "Improved" fuel economy with the use of N2.

It is well established science that any given tire will have improved (lower) Rolling Resistance (RoRo) with an increase in inflation pressure. RoRo is the force that impacts vehicle fuel economy with increased force resulting in lower mpg.

If inflating a tire with N2 results in a more stable (less increase due to temperature) inflation pressure, where is the data that shows that somehow the improvement in RoRo with an increase in inflation pressure no longer exists when the inflation gas changes from 78% N2 to 95% N2.

Not saying that constant inflation pressure with N2 doesn't result in improved RoRo, just haven't seen any data. Maybe someone can educate me.

[wolfe10]

Sorry, guys, but the Ideal Gas Law applies equally to N2 and DRY air. There is no difference in PSI change with temperature change between the two.

This is NOT new information: http://en.wikipedia.org/wiki/Ideal_gas_law

Brett

[N2TYRZ]

Tireman9 here is one study that I came across that is relating to rolling resistance and hopefully has some merit.

I promote proper inflation whether air or N2 and have had better results with N2 being drier due to many shops not using industrial air drier.

Both studies are the same but one is final report and one from the university site.

http://etd.lib.clemson.edu/documents/1202498590/umi-clemson-1432.pdf

http://getnitrogen.org/.../files/Clemson_NitrogenFilling_FinalReport.pdf

I am not affiliated with any company selling N2 equipment, I buy my N2 from our gas vendor very reasonable for 99.999% pure N2 which can't get from N2 units sold for under 10k.

[RVerOnTheMove]

Hard to sell snake oil when you have solid science that disputes all of the claims!

[wolfe10]

Though I did not read the whole report, two things caught my eye:

They linked reduced PSI with increase in rolling resistance-- something we all know. Indeed, if one does not maintain tire pressure, loss of MPG WILL result.

BUT, yes big BUT on page 58, they admit they compared "wet air" with Nitrogen: "The permeability of air in tires at higher temperatures is greater because air contains moisture. Water is usually present in the case of conventional compressed air. At lower temperatures, as a liquid, water occupies very little volume."

And at the bottom of page 58 they say: "However the change in pressure of both the inflation gases would be in a similar pattern if air used for inflation is dry."

So, as we have already discussed in this thread (and I believe all agree), if you don't check and maintain tire pressure, you will experience increased rolling resistance and loss of MPG.

But, testing "wet air" vs Nitrogen kind of stacks the results. I didn't see a comparisons of dry air vs Nitrogen or if is in the other study which I did not read, please point it out.

Also, if their contention is that Nitrogen gives less rolling resistance/ better MPG because use of air leads to under-inflated tires, many of us would question that premise. I know I check tires (TPMS) each time I drive. If more than 2-3 PSI low, I bring them back to spec-- NOT required very often!

If my skimming the material has lead to a misinterpretation, please let me know.

This statement is close to unbelievable-- and the reference (6) is a dead end: "The above results show that by using nitrogen inflated tires, the rolling resistance can be decreased by about 70%. Hence, for a reduction of 70% rolling resistance in tires, fuel economy can be improved by 23%."

Brett

[britz]

I know this thread is air vs. nitrogen . . . but what about CO2?

http://powertank.com/category.rv

[tireman9]

N2TYRZ

Please repost or correct the 2nd link it does not work.

I note the claim "nitrogen inflated tires improve tire life by about 50% and vehicle fuel economy by 23%." I find this hard to believe given the current level of effort and importance placed on rolling resistance by OE vehicle manufacturers. Many times a 1% improvement in Rolling Resistance is enough to gain a multi million dollar tire contract. In my article published in Tyres International I cover the status of Rolling Resistance and you can see that there is no room to see a 23% improvement simply by changing 28% of the inflation gas from O2 and CO2 to N2. If these numbers presented by a college student in 2007 were accurate we would see 100% of all new vehicles come with Nitrogen inflation, but we don't.

Another problem is the failure to use accepted test machines to measure Rolling Resistance but to rely on highly variable over the highway fuel economy calculations.

Reviewing the air leak tests I find it interesting that there was actually a pressure increase in fig 5.8 on pg 59 between the second and subsequent measurements. This to indicates some fault in the test procedure.

For the truck tire test three different vehicles with three different drivers and three different pressure gauges were used. It is expected that air will leak at each pressure measurement and anyone that has ever measured tire pressure knows that sometimes you get a good reading with minimal leakage and other times the leakage is greater. This is just another variable not taken into consideration.

The biggest problem I have is the use of pressure change to predict Rolling Resistance change and therefore it is assumed fuel economy would be similarly improved. The other assumption is that a vehicle operator would not adjust the air pressure in the tires back to the proper inflation but would continue to drive on a tire with lower inflation than specified.

Tire life is really a tread wear estimate. The results were based on a one month test of an estimated 2500 miles and an approximate tread wear of 0.005". Having done thousands of tire tread measurements I can assure you that contact measurement gauges are simply not accurate enough to provide reliable measurements at that level.

Bottom line. In my opinion inflation with N2 is not a bad thing. It is even theoretically a good thing but to make outlandish claims of 23% fuel economy improvement and 50% improvements in tire "life" are not supported by the data presented or by decades of tire and vehicle industry testing.