Does filling your tires with nitrogen save you gas? There is a large group of advocates who say yes. Here is why they say that.

A significant factor in poor fuel economy is under inflated tires. The EPA agency that monitors fuel usage has found that properly inflated tires can improve gas mileage by 3 percent. The EPA also estimates that 30% of the cars on the road have at least one tire under inflated.

It is estimated that under inflated tires are responsible for the loss of more than 2 million gallons of gas every day. A tire with low air pressure begins to flatten which creates additional surface area between the tire and the road. This increases friction between the tire and the road which results in the engine needing to work harder.

When an engine has to work harder it burns more gas. More tire surface due to under inflation means it takes more power to roll that tire. More power needed means less fuel economy. A tire that is correctly inflated is going to roll more easily using less power from the engine and less gas.

How does all of this relate to nitrogen? It has to do with how tires loose pressure. As has been described earlier under inflated tires require the engine to burn more gas. But why do tires become under inflated? It is a common characteristic of all tires, they loose air over time. That doesn't mean you have a leak.

Tires are made with permeable materials. That means that the small air molecules can escape from the tires over time. As the molecules of air escape the tire looses pressure. It is a natural occurrence for all tires. That is why it is suggested that you should check your tires once a month.

It appears that tires inflated with nitrogen loose pressure 3 times slower than tires with conventional air fills. This is because nitrogen has a higher density than oxygen. Higher density translates into larger molecules. Larger molecules will not permeate through the tire as easily as smaller molecules so nitrogen with it's larger molecules stays in the tire longer. That creates a slower loss of tire pressure over time.

Your car's tires will maintain themselves at full pressure longer when filled with nitrogen because the gas loss through the tire is so much slower. The result is tires that roll with less friction, and that translates into less gasoline needed to move your car which means better fuel economy.

The price to fill your tires with nitrogen is around $40.00 per set of 4 tires. Is it worth $40.00? Those who support nitrogen as a substitute for air say absolutely it is. There is, however another side to this issue. There are those that argue that it is not worth $40.00. It might be worthwhile to find out why critics of nitrogen suggest not using it before you commit to spending that $40.00.