Nitrogen, Myth or Fact
August 17, 2008 by Brad Sears ·
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First let me thank all that sent expressions of sympathy. My mother, an Rver from the way back machine, always said, “that there were no strangers in the RV fraternity, only friends that you had not met yet.”
Now on with the subject at hand, nitrogen in tires in place of plain old compressor air. I have rewritten this blog at least ten times from the politically correct view point, from the gloss over the facts point of view, and finally from the let it all hang out perspective. Now remember that my blogs are my own opinion as I have arrived at them from a study of the facts as I see them.
But we need a little background here. Yes my primary life’s work can be categorized as automotive education but my view of education was in places markedly different from the standard definition. If I was going to teach automotive technology I needed to know the industry inside out. That meant getting into the minds of the guys sitting in the board rooms, the sales meetings, design and engineering, marketing and advertising, the technical side, and the customer service end. As a result when things like this nitrogen wave comes along my mind begins to work.
Now in the last blog before my short hiatus we heard George say that switching to nitrogen was a no-brainer. Now I really like George, although I have never met him, but I need to express my views.
Lets look at afew of the claims.
1. Better fuel economy.
This claim appears to be based that all who still have air in their tires instead of nitrogen never check the air pressure and have not for years, all of them, have driven around on under inflated tires. Consumer Reports has tested the “loose less inflation” theory and found that over a year in their test that plain air lost an average of 3.3 PSI while nitrogen filled tires lost 2.2 PSI. If tires are checked monthly this hardly seams a difference worth the price of the nitrogen.
In the claims for nitrogen they state that there is less pressure deviation due to temperature. This indicates that when driving on a warm day that the tires will not build up as much pressure as a tire filled with air. To my mechanical mind this is built in under inflation over what the engineer designed into the tire. Hey, don’t blame me for this assumption I am only using the words supplied by those hyping the product.
2. NASCAR uses nitrogen to control tire pressure under heat better.
True, it works on race cars running 200 miles per hour. The tire patch on one NASCAR racing slick is bigger that the patch all four tires on your family car puts down on the pavement, More patch, more heat developed. 60 miles per hour vrs 200 miles per hour. Taking turns at the limit of adhesion with the pavement. And running a soft compound tread that sticks to the track. This point is driven home by the fact that at the NASCAR race at Indy this year they were wearing out tires every 25 miles of racing! Also at 200 miles per hour a driver can tell the difference in handling when tire pressure chages a quarter of a pound per square inch.
Now I could go on point by point and I’ll bet that when the comments start to pile up we will, but I want to touch on another point. Adding nitrogen to your tires is another in a long line of profit centers for the auto service industry. Years ago I was involved with a company the made automotive diagnostic and front end alignment equipment.
The sales reps were taught that the main focus on the sales call was return on investment. It was true that a shop could make more money in the front end alignment bay than with the guy that replaced clutches. Front end alignment was marketed and every 10,000 we were brainwashed that the front end needed to be aligned. In my last three vehicles with a total mileage of over 300,000 miles I have had the one front end alignment and that was when a tie rod end needed to be replaced on the pick up.
It is strange that catch phrases developed in the sales and marketing meeting becomes the accepted truth without back up or minimal back up.
As the manager of our local TV station says at the end of his editorial comments, “that is my opinion, what is yours?” Lets have some dialogue.
Brad
Last 5 posts by Brad Sears
- Grand Adventure part 3; Kansas To Seattle. - November 17th, 2008
- Unraveling The Grand Adventure part One - November 11th, 2008
- Squeezing The Gallon for The Last Drop! - November 6th, 2008
- Grand Adventure-Part One - November 6th, 2008
- The Inverter Is In And Miricles Of Miricles, The System Works. - October 16th, 2008
It’s easy to forget that ordinary air is almost 80% nitrogen, meaning that switching to 100% nitrogen only affects 20% of the gas in the tires. A chemist can imagine that replacing oxygen, a chemically reactive element, with nitrogen, an inert gas, might be easier on the rubber in the tires. However, I’ve never seen this claim, and I’m sure that if it had any merit it would be touted. The only possible advantage seems to apply to people who don’t check their tires for months at a time. If you don’t, how will you notice road hazard damage, uneven wear, ozone checking, or anything else that can damage a tire? Well, if spending the money for nitrogen takes you out of that bad habit, then go for it!
I would like to add a comment or two concerning the nitrogen issue. I have been associated with the industry and would like to add that I have not seen anything scientific supporting any of these claims of improvement using nitrogen. Nitrogen only goes inside the tires and only changes the percent of nitrogen from approximately 80% to 95+% on the INSIDE. What about the other half of the tire that is exposed to the elements? Do tires wear or weather from the inside or the outside? Think about it before you throw your money away.
OK I’m the “no brainer” guy that was referred to as George. I accept the following:
-Rver’s do not drive at NASCAR or Formula One speeds.
-An RV does not have to “land” at 200 MPH.
-Nitogen does leak somewhat.
-There are possible other reasons to question the value of using the gas in lieu of air.
HOWEVER, Let’s assume that the positive claims made are only 50% valid.
-My Fifth Wheel weighs 16,000 pounds loaded and cost the bank over $85k
-My truck is a heavy brute and as is cost the bank over $60k
-Under inflation and tire failures in general are a significant cause of RV incidents and that puts $145k at risk not to mention my skin.
-Running cooler at 65 MPH while jousting with 18 wheelers on the interstate seems to make sense.
It cost me just $90.00 to fill seven truck and five RV tires with nitogen. Even at just 25% truth in favour of nitogen over air. Yep, it’s a no brainer to me.
Gord AKA George
Another factor, not yet mentioned, is that the water vapor present in the compressed air will expand more than a dry nitrogen dispensed from a cylinder.
This will account for a greater pressure rise than in either dry air or nitrogen alone.
A George…er.. Gord I changed the name to protect the innocent but you stepped up to the plate anyway. Thanks for being a good sport. You have hit the nail on the head about maybe 50% of the claims being true. And I question this practice and I was part of that way back in the 70’s and 80’s. But that is a story for another blog. Now, about the tires running cooler with nitrogen I cannot find any test results to back that up and those that I talked to in the industry getting ready to write this piece admit that the cooler running is an assumption that tires without nitrogen are running under inflated.
Red Rover I covered that point in the origional blog.
Harold and Casey you both make valid points.
Keep the comments comming.
Brad - Thank you for a concise summary of the pros and cons of nitrogen vs. free atmosphere for inflating rv tires. I am an informed layman, not a scientist or a educated tire tech, but your conclusion that there is little difference between the two as an inflator makes good sense. To overwork a ’60’s phrase, do what ever turns you on.
Interesting subject!
I have a 19000 lb fifth wheel and an F-550 to pull it. I use Pressure Pro tire sensors to monitor my tire pressure and check them every time I fire up the engine. Concurrently, I use a Power Tank (Google it) to fine tune my tire pressures and it uses CO2. As far as I’m concerned (and I’m a retired chemist) there is no difference in performance between air, N2 and CO2. My system allows constant surveillance and the ability to adjust pressures anywhere.
Nuff said!
in Oct 2007 I had 4 newGoodyear Marathon tires installed by Sam’s
Club. They installed Nitrogen in all 4 at no charge. I didn’t take the fiver out until we left for Arizonia in Mid January. Before leaving I checked the tires. All four were about 45# Sam’s had filled them to 65# Temp or just setting? A 20# loss in 3 1/2 months. I’m glad I didn’t pay xtra for nitrogen.
I have 2 points to make.
Yes we use nitrogen in aircraft tires but we do it because of the ambient temperature. At altitude the water vapor in the tire will freeze and on landing it could give you an out of round condition.
The second point is actually a question. When you get nitrogen installed in your tires and they are low what do you do? Do you ride on the low tires till you can find nitrogen or do you fill it with air and then dump all the air and refill with nitrogen?
I’m a believer that 20% oxygen is not going to change the dynamics much
Some comments from a Tire Engineer.
Do not confuse lower pressure build up (primarily do to dryer inflation gas) with lower heat build up. While I haven’t done a specific test, my personal experience confirms less pressure build with dry N2 in place of air from a compressor. BUT tire heat is a direct function of tire deflection plus tread slippage. If slippage (cornering) is held constant then all we have is increase in heat generation due to more deflection. Lower inflation means more deflection. Dryer inflation medium means less inflation build so it follows that it is entirely possible that the lack of pressure increase could lead to hotter tire operating temperature.
Brad hit the nail on the head when he pointed out that much of the marketing of N2 is based on the fact that tires inflated with N2 lose pressure slower than tires inflated with “air”. Since people don’t check or adjust their inflation then it follows that inflation with N2 and poor maintenance is better than inflating with air and poor maintenance.
If you check your tires at least once a month, or more often, as recommended by tire industry and auto industry, then I don’t see the possibility for inflation with N2 to be measurably different than with air.
I have heard of a test that shows that since the Oxygen “leaks” out faster than the N2 as time goes on and you keep adding air the % N2 does go up a fewe points. You will never get 100% N2 and the best I have heard of is 97% with 4 purges required.
Bottom line. Nothing wrong with using N2 but you still need to check and adjust your inflation at least every month with air or with N2.
Thomas
20psi loss in 3-1/2 months in each tire? Something is wrong unless you didn’t check the tires 24 hours after the initial inflation.
Normally new tires will show a decrease in pressure in the first 24 to 48 hours of 1% to 3%. This is due to tire growth. The increase in volume results in a decrease in pressure.
I would have expected to see something like 5 psi drop.
Keep an eye on your tire inflation and check VERY often. You could have leaky valve or some other problem.
I feel it needs to be said to the people who claim that they are in the business that you should get out of the cave. I see trucks on the road all the time and talked with these drivers and service people for some time, as well and yes i have been in the indusry now for over 30 yrs in many differant postions, from line mechanic to sales to some light engineering to racing. so i am not talking like i do not know. Yes nitrogen dose help in a number of ways and yes it is minimal at best so each of you need to weight it out, yes there is some facts that are being pushed by the fact of money ( marketing) but so is everything else in this country, this is a capialist country. As for the statment from My Sears about not needing a front end alginment well i am glad he likes to drive hanging onto the wheel as it pulls in either direction and also wears out his $100 plus dollor tires.
Well let me answer a couple of these comments:
Red Rover, my understanding of thermodynamics is that you are correct to a point. The expansion rate occurs after the water has reached the point of vaporization or steam. And I hope that none of our tires get to 212 degrees F. Also as seen in boiler operation it takes a great volume of water to create steam pressure.
Brooker, if you read your comment and the origonal blog you and I are more on the same page than not. As far as wearing my tires out, I check tread depth at least each thousand miles, tire pressure weekly, run my vehicles over my old Bear scuff gage that I kept when I sold my shop at each oil change, and Tommy Knock my tires at every stop when traveling as well as an infra red tire temperature check. What I was getting at was two fold, we were sold a partial bill of goods in years past and with improvements in tires and vehicle engineering we are no longer on the 10,000 schedule for alignment. And lastly I am sorry to add that being a capitalistic society does not excuse not telling the truth.
And a question for Thomas:
How far did you have to drive on low tires to add nitrogen to the tires?
I think the reason we use nitrogen in tires is to eliminate all of the air which contains moisture.
Moisture plus tire rims equals rust or corrosion the enemy of all metals.
So if we have 99 percent nitrogen and 1 percent air are we going to get rust?
Eventually, yes.
Seems to be an all or nothing deal.
Aircraft require nitrogen in their landing gear struts which just happen to be next to the tires; one cylinder does both.
Boiling point of water is 212 at sea level or at 14.69 psia or 0 psi gauge.
In a tire operating at 40 psig the boiling point of water is about 286 F.
http://www.engineeringtoolbox.com/boiling-point-water-d_926.html
While the moisture can affect the inflation pressure of a tire it will not turn to steam due to the increased pressure.
Aircraft use Nitrogen for fire safety reasons due to high loads, high speeds and high brake temperatures and the potential for a tire fire where high pressure air can contribute to the fire while Nitrogen will not support combustion of the tire.
Re racing, some current Indy car teams use Nitrogen, it has been reported that some use desicated (dry) air. They have the data so they can calculate and adjust the cold inflation to get the hot inflation they want.
I believe you will find that “bottles” of Nitrogen are readily available and inexpensive but I think you will have some difficulty finding bottles of air, so this is one reason we used N2 in my race team.
We inflated tires and ran our “air” tools while at the track as having a bottle of N2 was much preferable to taking along a gas powered compressor and the N2 was more reliable and we could get more CFM when we needed it while the small compressor just could not keep up.
A tire with 36psi of air will have identical rolling resistance (fuel economy) to a tire with 36 psi of Nitrogen or 36 psi of Argon.
Actually, Roger, if you were a scuba diver you would know that “bottles” of air is quite commonplace in that sport.
Thanks Tom
I had forgotten about scuba as I was thinking of the 5′ tall 250 CF 2000psi tanks not your smaller tanks.