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The convert formely known as Lexusfreak
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Interesting article I thought...


Better mileage through nitrogen?

by David Sharp, Associated Pressposted July 31, 2006 TOPSHAM, Maine (AP) — Many motorists seeking to improve their mileage as gas prices soar this summer are examining everything — right down to the air in their tires. And for a growing number, plain old air isn't good enough.
George Bourque of Fairfield is one of those who's driving around on tires filled with pure nitrogen, the same stuff that NASCAR racers use.
Bourque, an engineer, said he has seen a 1 to 1.5 mile-per-gallon increase since he began filling his tires with nitrogen, which is touted as maintaining tire pressure longer and resisting heat buildup on hot summer days.
"I analyze everything," he said.
Nitrogen has been used for years in the tires of race cars, large commercial trucks, aircraft and even the space shuttle.
But it is finding its way into the mainstream at a growing number of tire dealers — including Costco Wholesale Corp.
Nationwide, fewer than 10 percent of tire dealers offer nitrogen, but the number is growing, said Bob Ulrich, editor of Modern Tire Dealer magazine in Akron, Ohio. Most dealers charge $2 to $5 per tire for the nitrogen fill-up, he said. The dealers generally offer free lifetime refills.
Bourque got his tires — filled with nitrogen — in Waterville, Maine at Tire Warehouse, which has 50 tire dealerships across New England. The nitrogen was part of an installation package when Bourque bought a set of tires.
Skeptics will question how much can be gained by filling tires with pure nitrogen when the air we breathe is 78 percent nitrogen.
The differences are subtle, but important, said Steve McGrath, Tire Warehouse's vice president of marketing in Keene, N.H.
Nitrogen molecules are bigger than oxygen molecules, so nitrogen seeps out more slowly from tires than air; nitrogen resists heat buildup better than air, which contains moisture; and nitrogen reduces oxidation, which can damage the tire from the inside out, proponents say. Nitrogen is an inert gas, so there are no safety or environmental issues.
Those advantages are important in vehicles equipped with tire pressure monitoring systems, which are sensitive to changes in tire pressure, McGrath said.
With or without nitrogen, proper inflation is the key to improving gas mileage. Motorists can improve gas mileage by 3.3 percent simply by keeping their tires properly inflated, according to the U.S. Department of Energy.
In the real world, though, only 1 in 5 motorists check tire pressure regularly, according to the Rubber Manufacturers Association. Nitrogen, therefore, could have an advantage for those who don't check their tire pressure regularly.
The National Highway Traffic Safety Administration has no opinion on nitrogen, but it does encourage motorists to keep their tires properly inflated, both for safety and to boost gas mileage, said spokesman Rae Tyson. Severely underinflated tires are dangerous, especially for sport utility vehicles and light trucks, Tyson noted.
Tire experts at Consumers Union, publisher of Consumer Reports magazine, neither endorse nor object to the use of nitrogen in tires.
"Nitrogen is certainly safe to use in tires, and theoretically it does offer some benefits," spokesman Douglas Love said from Yonkers, N.Y.
For Bourque, his tire pressure remains constant — 40 pounds for his fully loaded truck — even on hot days when tire pressure normally fluctuates.
His gas mileage was about 19 mpg when he purchased his five-cylinder 2005 Chevrolet Colorado. Now, with the engine broken in and new tires filled with nitrogen, he gets 20.5 to 22 mpg depending on whether he runs the air conditioner, he said.
For tire dealers, the nitrogen generator and associated equipment typically runs between $3,000 and $12,000, Ulrich said.
Marty Mailhot, manager of the Tire Warehouse in Topsham, said the idea is catching on with consumers, who are purchasing nitrogen for tires for cars, trucks, motor homes and lawn tractors. He has even tried it on footballs and inflatable tubes pulled behind boats.
He has a retort for those who pooh-pooh the notion of paying for nitrogen when there's plenty of free air for the taking.
"I say, 'Why are you drinking that bottled water when there's a pond out back?'" he said.
 

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For Bourque, his tire pressure remains constant — 40 pounds for his fully loaded truck — even on hot days when tire pressure normally fluctuates.
His gas mileage was about 19 mpg when he purchased his five-cylinder 2005 Chevrolet Colorado. Now, with the engine broken in and new tires filled with nitrogen, he gets 20.5 to 22 mpg depending on whether he runs the air conditioner, he said.
Interesting, but hardly scientific. "now that the engine's broken in" and the fact that he switched tire compounds seems to speak volumes.

That being said, keeping your tires properly inflated is not only good for mileage, but also for safety, and if using nitrogen means you don't have to check as often, then i'm all for it. For people who aren't as obsessive about their cars as us enthusiast types, it may be a good idea... and I'm sure we all waste $10 on more useless things on a regular basis.
 

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I run nitrogen in my tires, not for any specific reason, just because i work for an industrial gas plant, and we happened to have a nitrogen tank with a tire adapter on the end of the hose for the truck tires (and we only do this because it's cheaper and easier for us then buyin a compressor). I guess the nitrogen is nicer cause the pressure doesn't fluctuate with temperature, but other then that i never really noticed a difference between runnin air and Nitrogen...
 

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Nitrogen has been debated a few times, but it is true that it doesn't expand and contract with heat changes like regular air will.
 

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Dodgy Post Whore - eh!
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Associated Press said:
The differences are subtle, but important, said Steve McGrath, Tire Warehouse's vice president of marketing in Keene, N.H.
Nitrogen molecules are bigger than oxygen molecules, so nitrogen seeps out more slowly from tires than air; ...
Wikipedia here I come...
Wikipedia said:
Nitrogen:

Covalent radius 75 pm
Van der Waals radius 155 pm

Oxygen:

Covalent radius 73 pm
Van der Waals radius 152 pm
Well, what do you know, it is. By a whole 2% (roughly).

Edit: Since nitrogen is about 4/5 of the atmosphere anyway, the 20% of 98% means pure nitrogen will leak out 0.4% more slowly than ordinary air. And since ordinary air doesn't leak very much at all from ordinary tyres...

Associated Press said:
... nitrogen resists heat buildup better than air, which contains moisture; ...
From memory, air contains about 1% moisture content. It's already vapour but I suppose it could still make a difference when it heats up. But my old Mazda handbook said increase pressure for high speed (ie, hot tyre) driving. So having the pressure "automatically" increase when they're hot seems like a good idea.

Also, if I understand the Wikipedia info correctly water vapour takes 63 times as much energy as nitrogen to raise it a degree, so should provide a stabilising influence on tyre pressure. Does it expand much more than nitrogen for the same temperature difference?

Associated Press said:
His gas mileage was about 19 mpg when he purchased his five-cylinder 2005 Chevrolet Colorado. Now, with the engine broken in and new tires filled with nitrogen, he gets 20.5 to 22 mpg depending on whether he runs the air conditioner, he said.
What Blitzoid said.

Associated Press said:
Marty Mailhot ... has a retort for those who pooh-pooh the notion of paying for nitrogen when there's plenty of free air for the taking.
"I say, 'Why are you drinking that bottled water when there's a pond out back?'" he said.
Which is a non sequitur. However, the response to his statement is "So why are you breathing atmospheric air when you can buy bottled air?"
 

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techy101 said:
Nitrogen has been debated a few times, but it is true that it doesn't expand and contract as muchwith heat changes like regular air will.
I edited that to be more accurate. Nitrogen expands and contracts like any gas with temperature, however I'm not totally sure if it acts similar to an ideal gas by itself, my guess would be yes. If so, the ideal gas law as a (maybe) reasonable estimate of volume change (or pressure change) is PV = nRT. The difference in expansion of nitrogen compared to good old 'air' is going to be miniscule. Like sheepish said, the water vapor will act as a buffer to the expansion of the gas.

Is there a difference putting pure nitrogen into your tires versus compressed air? Yes. Is the difference something that is even remotely noticeable on any effect of the driving of a car (tire pressure, etc), HIGHLY unlikely. I'm a chem major and if I get bored I'll look up some heat capacities and compare expansion of the two gas 'mixtures'. My feeling is that the difference is going to be so small in percentage such that it would be negligible. Pchem to the rescue....

The guy said himself he changed tires between testing AND the motor was fully broken in during the "testing" of nitrogen so that test is totally bogus, not even any semblance of a "control". I could do a lot of things that would make it appear like it gave me better gas mileage, including putting a block of wood under the gas pedal. :icon_wink: That was a lovely ad to get people to buy compressed nitrogen for no reason though, they must have a surplus somewhere...

-Steve
 

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I know that the general rule of thumb is that for every 10 degrees F you gain or loose one PSI up or down respectivally. Track days can cause tires to dramatic heat changes, so I might see it being useful there. Personally, I won't bother, but I do believe that there are some benifits.
 

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the nitrogen is "dry" meaning no condensation in it, air from a compressor does(especially from a gas station.) the moisture inside is usually what contributes to fluctuating pressures due to vaporization etc. also, notrogen would help preserve the inside of the rim by displacing this moisture.
 

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It really not an advantage because air is made up of mostly nitrogen.
By volume, dry air contains*78.09%*nitrogen,*20.95%*oxygen,*0.93%*argon, 0.04% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere.

Laughing at oneself and with others is good for the Soul
 

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Nitrogen is a gas, it adheres to the Ideal Gas Law, as it warms it will expand. This is fact.

Nitrogen is pointless for use in tires for many reasons stated above, I will add this, however:

Nitrogen will age the tires more slowly because as molecules leak out of the tire between the bonds of the rubber molecules, nitrogen will oxidize the rubber more slowly than regular air.

(Bleed all the air out of your tires and double bag them when in storage for the same reason. Creates a micro climate that slows the aging of the rubber.)
 

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Costco uses nitrogen with all tires that they install and during later service.

Last set of tires lasted to 75k... what they are warrantied for that’s unusual for me in South Fl.

Was it Nitrogen?
 

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The reason as I see it are the lack of moisture and oxygen. Which are beneficial. But not that big of a deal all things considered.
 
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