Monday, January 16, 2012

Don’t Pay for Nitrogen In Your Tires

It’s bad enough that gas stations now make you pay to inflate your own tires with air. But at least you are getting what you paid for…air which does what it’s supposed to do and that is to keep your tires inflated.

Many car dealers are now charging customers to fill their tires with “pure” nitrogen. They tell you that nitrogen does not leak from your tires as quickly as air and this means that your tires will stay properly inflated longer before you have to add more nitrogen (and pay the dealer for this). What the dealers don’t tell you is that the air that is already in your tires is mostly nitrogen anyway. In fact, 78% of the air you breathe is nitrogen. Oxygen represents only 12% of the air. The rest of air includes carbon dioxide and other inert gases. I’m not sure what the purity of the nitrogen is that they pump into your tires for $199 (this is not a typo…one hundred and ninety-nine dollars for filling four tires full of mainly air). But, you can be assured that the purity of the nitrogen is not 100% and is probably closer to the 78% that regular air consists of.

Even knowing all of the above, I have to admit that I was curious about whether or not nitrogen could prolong tire live and improve fuel economy because I knew that NASCAR drivers used nitrogen filled tires and I heard that Volvo’s came from the factory with nitrogen in their tires.  I have a BS in Physics from the University of Florida and a Master of Science from Purdue and these kinds of things interest me. So, to find out for myself, my dealership conducted an experiment. We have a fleet of rental cars and we filled two tires of each car with pure nitrogen and 2 tires with regular air. Over the course of many weeks, we measured the pounds of inflation in the nitrogen and air filled tires. There was no difference in the inflations of the nitrogen v. s. the air filled tires. If there is no difference in the inflation, there can be no benefit from nitrogen of better gas mileage or fuel economy.

You may have read my column last week, “Beware the Phony Monroney”. In that column I warned you about car dealers that add a window sticker designed to look exactly like the federally mandated Monroney sticker. This is where you should look for dealer installed accessories and additional dealer markups over MSRP. Often these accessories have a high price but a very low cost. In the case of nitrogen in four tires selling for $199, this is exactly the case. Since air is already 78% nitrogen, it costs virtually nothing to extract nitrogen from the air. To be generous, let’s say the dealer’s cost is $10 including labor. That is a 2000% markup when he charges $199.

Just when I thought I’d seen it all, I actually saw window stickers on a car today from another dealer who had actually modified the Monroney label to show nitrogen filled tires. To do this, the dealer actually had to remove the real Monroney label, make the modification showing the nitrogen tires, and re-paste the Monroney label to the window. Federal law requires that a Monroney label not be removed until the vehicle is delivered to the customer. It also requires that it not be modified. This new vehicle was one we had traded for from another dealer and still had the counterfeit Monroney and the modified real Monroney attached to the window. The modified Monroney looked so authentic, that one of my technicians and my service manager inquired of Toyota about the necessity of our carrying nitrogen tanks so that we could refill these tires with Nitrogen. If this could fool a Toyota dealer’s technicians and service manager, it might fool you too.

This particular dealer also had another charge added to the counterfeit Monroney sticker, a $4,995.00 “Market Value Adjustment”. Most prospective customers think that this is part of the manufacturer’s recommended retail price. They either end up paying too much money for the vehicle or think they are getting more for their trade-in or a bigger discount than they really are. It’s easy to allow someone an extra $5,000 on their trade-in when you have already marked the car up an extra $5,000 over sticker price. 


  1. I was in agreement with your figures, except that oxygen represents 21% of the sea level atmosphere. Perhaps 12% was a typo? Paul McDowell

  2. Thanks very much for catching that typo, Paul.

    Actually the amount of oxygen is not quite 22%, but close. There are also some other inert gases in the air we breathe,1.25%, inert gases. They are Argon, Neon, Krypton, and Xenon.

    Of course, the point of my article is that you are already getting mostly Nitrogen in the air you fill your tires with. To pay money for pure Nitrogen is silly.

    I will make the correction from 12% to 22% for Oxygen.

  3. I think nitrogen tires are really useful as alternatives.
    It is sturdy and a great durability.

  4. Dear Cheap Tyre Changer,

    Google "Consumer Reports and Nitrogen", read the articles and you will change your mind about Nitrogen being a "useful alternative".

  5. Hi Mr Stewart,

    I wish that my first experience as a Toyota Sales Consultant was working for you. Instead I got my first taste of sales for a dealer that has a $699.50 dealer fee, $700 new car pack, charges for Nitrogen in the tires, steals trade in, offers a terrible play plan and floods the sales floor with staff that doesn't know any better. I was one of them. I don't know what it's like to work for you or how things are behind the scenes with the sales managers but I have a feeling that it's a bit better than my experience.

  6. Dear Dwayne,

    If you like to sell cars and are good a it, we would love to talk to you. I's a good sign that you have a conscience and what the other Toyota dealer asked you to do was of concern. I could tell you how well we treat each other at Earl Stewart Toyota, but my suggestion would be for to ask any of my employees. Our culture is to treat each other just like we treat our customers...with courtesy, respect, and integrity. But don't take it from me, ask anybody that works for me.

    Just call 561 844-3461 and ask to speak to a salesman. Tell him or her that you're thinking about applying for a job and ask what she thinks of working for Earl Stewart Toyota.

  7. These scams prey on the elderly and uninformed. I researched this - they use 95% Nitrogen (remember 78% in air to begin with). While Consumer Reports showed a minor difference in pressure loss, it's not al all worth the premium paid for Nitrogen. In either case, you need to add gas to your times occasionally. If you use Nitrogen, you will be paying for that privilege and find it difficult to locate a place. Stick with air.

  8. I feel that you're overlooking the cold winters. Regular air filled tires in consistent -20oC to -40oC temperatures lose quite a lot of pressure. I switched to nitrogen filled winter tires for our long season in the north and there is -absolutely- a significant difference in tire pressure during those months.

  9. Dear Mr. "Phooey" (Love your name)😊

    I understand and appreciate the point you're making.

    However my opinion on nitrogen in tires relies heavily on the Consumer Reports one-year study which you can reference online. I've lived in Florida most of my life and haven't had much experience driving in very cold temperatures. A listener to my weekly radio show called me several months ago and mentioned that he found nitrogen in tires useful in the cold weather. He said that, with regular air in his tires, his "low inflation tire indicator" warnings on his dash came on too often when the temperature dropped. Using nitrogen this did not happen as often.


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