If you're like most people you don't check your tire pressure on a regular basis. Some people never check it (you know who you are). A lot of modern cars have monitoring systems that tell us if our tires are not properly inflated so they never think about it unless the warning light comes on.
There's no arguing that maintaining proper tire inflation helps maximize fuel efficiency as well as tire life. The question is, how feasible is it for everyone to fill their tires with nitrogen instead of air. If you can get it for free, why not do it but I think most places charge for nitrogen.
Proponents of nitrogen filled tires say it would increase average fuel efficiency because everyone's tires would stay properly inflated longer than if they were inflated with just air. Obviously this refers to the natural tendency of people to ignore their tires, some out of laziness, others out of apathy.
The idea is that nitrogen diffuses out of the tires more slowly than oxygen. Most manufacturers recommend a nitrogen concentration of 93-95%.
So, I'm wondering if any of you out there uses nitrogen in your tires and if it is worth the money (if you pay for it). If I could get it free I would use it.