As a Toyota dealer, we field quite a few questions about tire pressure, but there’s a new one being asked. Some of our customers have heard that filling their tires with nitrogen could have some beneficial effects. Since we’re always up for a challenge, we looked into it and this is the information that we found.

The air you are breathing right now is over 70% nitrogen. Your Toyota dealer has learned that you don’t really need quantities of oxygen in the air over about 21% in order to breathe well. Because of just how much nitrogen there is in the air, it’s a relatively easy gas to come by. Really though, why would a person want to use it in their tires?

No matter how well sealed your tires are, air escapes. It can make it through the stem cap over time, it could find a leak, and it can also slowly make its way through the rubber of your tires. All matter has gaps between the molecules, and air can exploit this. The thing about nitrogen, your Toyota dealer has learned, is that its molecules are larger than oxygen ones. The larger the molecule, the less air will be escaping, or so the theory goes.

So, is this really true? Well, we at your Toyota dealer couldn’t find any proof that it does. The theory is sound, but we could only find opinions and anecdotal evidence. All the same, there is the fact that standard air tends to be about 5% water vapor that expands and contracts with temperature. Because of this, a nitrogen filled tire begins to sound like a really good idea.

There is another thing to consider, however. Filling your tires with nitrogen doesn’t come cheap. Instead of free air with a fill up or a few quarters for the pressurizer, nitrogen inflation can cost up to $10 per tire, which can really add up.

So, for our money we’d stick with plain old pressurized air. It may not be as glamorous, but without real proof that nitrogen inflation is a better bet, we just don’t think it’s worth the cost.