The Coalition of the Swilling

The differences are subtle, but important, said Steve McGrath, Tire Warehouse’s vice president of marketing in Keene, N.H.

Yup....you pay for the nitrogen gas, whereas air refills are much cheaper. Which, no doubt, Mr. McGrath wants you to ignore.

There's a trade off here, tire life and gas mileage versus the higher costs for nitrogen, a benefit-cost analysis that I haven't looked into. But with that 1.5 to 3.0 MPG increase cited in the article (nice but not spectacular), I'd guess that this might be a break-even deal in the long term.

NASCAR drivers push their vehicles to the upper limits....they need every edge they can get, as there is very little to no room for error. Under those conditions, nitrogen filled tires makes sense.

For the typical motorist? Sounds like a fad.

Well, the tire types they talked to said they charged for the intitial filling, then refills were free, if I remember correctly. And if you're a person who bought one a them big ass honking Avalanches for your everyday car, 1-3 more miles a gallon would probably make yer day. The improvement would be like an extra gallon of gas.

Avalanches (el al.) would not get 1-3 mpg more. They would get about 3% more mileage than what they currently get (if they currently get 20 mpg, that's about 0.6 mpg).

I'm not too impressed with the molecular diameter argument, it's 0.31nm for N2, 0.29nm for O2. I don't remember permeability equations but that strikes me as pretty minimal. Nor do I buy the "heat buildup" argument. I suspect any benefits are pretty marginal.

What does make some sense is the oxidation argument, but my own experience (and the continued existence of retread tires) suggests that oxidation from the inside is not a big problem.

I only notice the mistakes - for example, where the (heh) journalist says, "Nitrogen is an inert gas, so there are no safety or environmental issues."

One - nitrogen is NOT inert. It's right between carbon and oxygen on the periodic table.

Two - an inert gas doesn't mean "safe, no environmental impact," it means "does not readily form chemical compounds." If you think argon is safe for the environment just because it's inert, try breathing some.

Still sounds like a fad to me, THS. And if someone blows $30,000+ on a car, I have to wonder if they will worry about saving a gallon of gas a day.

And if they are worrying about a gallon a day, then maybe they shouldn't have bought the car in the first place.

Oh, you guys always know everything. "Molecule this" and "inert that" and "I'm not worthy." Takes all the fun out of it.

THS, you is discussing teknekul stuff. That brings the men out of the boys, didn't you know?

You're supposed to check the air in the tires??

I read about a guy who did a paper about auto mechanics, especially the shade tree type. There is a lot more folklore to cars and how to maintain them than people like to admit.

-Daddy did it this way, so I will too, no matter that synthetic oils virtually never degrade, I'm going to change it at 3000 miles without fail, and 100 miles after I buy the car too.

-No matter that there is no such thing as a need to baby an engine when it is new, I'm still going to avoid finding those warranty issues by not stressing the engine while its new.

There's also the people who want to do something to show how much they care about their car, no matter that it does nothing for it. K&N filters, and nitrogen in the tires are prime examples.

If it makes them happy to spend money on their car, good for them. But it does nothing for the car.

[Grumbles because this comment apparently didn't go through before]

Fly, the guy is right. Nitrogen is inert, for all practical purposes. Its triple bond is so tight that the activation energy required to break it is too high for it to form bonds under normal circumstances. It requires a particular type of bacterium ("nitrogen-fixing") to move it from the elemental form to compounds useful as fertilizer.

Likewise on the environmental issues. It's effectively inert so it has no impact at all. Same for argon (you can breathe it just fine, as long as it's mixed with oxygen). Same for any other non-inflammable, non-poisonous gas.

Argon being one of the 'noble gasses', unlike the everyday gasbags I'm sure you usually run into, Diptera. Like on trips for a Philly Cheesesteak Shop, at bars ~ that sort of thing.

You know, seriously, what the world needs is more chemistry blogging.

"1 to 1.5 mile-per-gallon" Who the hell cares, it won't get me into Winnemucca from Reno. I think there are more instant-Wiccans in Kragan Auto Parts than anywhere - people will believe in witchcraft, Marvel Mystry Oil, PTFTE and any super-additive or bolt-on strap-on thingy. It's all salami in a sock.
I've seen the results of K&N filters on a dirtbike, it's bad, they kills motors - they offer little resistance to dirt-ingestion resulting in oval cylinders, we had a whole big thread-fest on rec.motorcycles.dirt about them ten years ago ('96'97). A fleet manager watched his trucks with K&N filters die.
Anyhow MPG is a pissing contest that misses the real point, it's not how far the stream goes, it's the size of the hose... ;-)

Agreed, Mr. Summers. I try my best.

Hoses, stream, salami, strap-on-thingees ~ get your mind out of the gutter, snipe! (What's a K&N filter?)

K&N's - not a lubricant mind you, are gauzy, tissue-paper-thin air-filters. Might as well go direct-air injection with a blower and keep a small supply of engine blocks handy. Hell, swamp-water injection while you at it! :-)

Ken - I blog corrected. Long live ChemBlogGuy!

You guys sure like to pick apart the K&N air intake systems, but has anyone actually tried one, I have. And I will never put a different filter on my vehicles. I put one on my 03 silverado. I had 20,000 miles on it when i put one on. I now have 75,000 miles one it. my fuel milage went up from 14.9 MPG to 18.5 MPG!!! And absolutely no engine problems(actually runs smoother). I also recently put one on the Grand Am and went from 28 MPG to 31.2 MPG. On the truck I go about 95 miles farther on ONE TANK of gas, That saves 6.3 gallons on one tank, and @ 3.20 a gallon thats about $20.00. I put on 22,000 miles a year and it saves me $920/yr or about $77/Month That is awsome. clearly pays for itself!!! Plus more POWER. Try one out you will be impressed. I know I was scepticle at first but I am now I true believer and very impressed.