Not all car tires have regular air in them, some of them have nitrogen. If you ever walk by a car and notice that the valve stems have green caps, you’ve probably seen a car with nitrogen in the tires. Are you wondering why someone would want nitrogen in their tires? Well, we asked the folks at Patrick Cadillac of Schaumburg, IL, a full-service Cadillac dealer, about nitrogen and they gave us the whole story.
Nitrogen is referred to as an “inert gas” by scientists because it doesn’t react with other substances. Contrast this with oxygen, a highly-reactive gas that tends to react with everything. For example, when oxygen reacts with steel, it turns to rust. Nitrogen, on the other hand, does nothing when it is exposed to steel. It doesn’t react with other substances.
Somebody some time ago reasoned that if you filled tires with a chemically-inert gas, such as nitrogen, you would have a sealed environment where no “aging” occurs. The result would be that inside of a tire would be permanently “like new”. A very interesting idea that may have some truth to it. Unfortunately, no one has done any research to verify this.
Better fuel economy
The theory is that since nitrogen loses pressure slower than air does, your tires are likely to stay at the correct pressure when filled with nitrogen. The EPA has indicated that under-inflated tires may worsen gas mileage by 0.3 percent for each 1 psi drop in pressure of all the vehicle’s tires. So, nitrogen-filled tires can indeed save you money because they stay inflated at the proper pressure longer than air-filled tires do.
Moisture Doesn’t Exist
Air has moisture in it. If you add compressed air to your tire, water comes along for the ride. The argument is that if your tires contain a lot of moisture inside them, this might accelerate corrosion and rusting inside the rims. The solution is to pump in pure nitrogen. Since nitrogen does not carry moisture in it, the internal environment inside a nitrogen-filled tire is absolutely dry.
Where can you get it?
Many vehicle dealers offer nitrogen as an “upgrade” on tire service. Prices for this will vary, of course, but recently we’ve seen the cost being around $8-10 per tire. You may also find nitrogen filling available at Jiffy lube and other independent lubrication and service businesses. When this article was being written, Costco was offering nitrogen fills as a complementary feature with tire service.