We've already mentioned (here
) that tires that are not properly inflated have a higher rolling resistance and make a car's engine work harder, burning more fuel and polluting more. Here is a tip to make keeping your tires are the proper pressure easier: Nitrogen! "The science is simple: Nitrogen molecules are bigger than air molecules, so they leak out more slowly and tires stay inflated longer. This inert gas, which makes up 78 percent of the atmosphere, has been used for years to inflate high-performance tires on race cars, military vehicles, giant earth-moving equipment, even the space shuttle." It is possible to buy a pump that filters nitrogen from the air, and some businesses like Costco and America's Tires have started filling the tires of their customers with nitrogen at no extra charge over a year ago.
Nitrogen leaks out of tires about 30 percent to 40 percent slower than air, according to Ingersol-Rand Co., which makes nitrogen inflation systems. And it doesn't hurt anything to pump regular air into your nitrogen-filled tire.
Also, since properly-inflated tires wear out slower and are less likely to fail, this can lengthen the life of your tires and make your car safer.
Update: Some good points were made by an anonymous reader in the comments below. As usual, it is sometimes hard to know what is fact and what is not, especially when supposedly professional journalists write about it (see the links where we originally got the story). In any case, the biggest benefits will come from keeping your tires well inflated (as we said here), whatever you inflate them with. In light of what has been written below, it does appear that nitrogen does not have the benefits that are claimed by our original sources.
::Nitrogen: It does a tire good, ::Nitrogen-filled tires are safer, can save money, ::Proper Tire Pressure For Better Mileage