**Before I address this month's topic, I want to remind everyone about S&S's Harvesters Food Drive. We are well on our way to filling our barrel, and have received many checks, which S&S will match up to $1000. Please bring us by at least 4 canned food items, and while they last, you will receive a nice reusable shopping bag courtesy of S&S Service Center.**

Would You Like Regular Air or Nitrogen With Your Tires?

You may have seen the articles about filling your tires with pure nitrogen to gain fuel economy and reduce tire leakage. And all of this only costs between $3 and $25 per tire. The reasoning behind these recommendations is that the molecular structure of nitrogen is such that it will not seep out of the tires as fast as regular air, so tires will "always" be inflated to the proper pressure. Sorry, but "regular air" is 78% nitrogen already, so it is of little consequence. Simply checking your tire pressure once a month and filling with air will save lots of money.

Another argument for nitrogen is that the pressure will not vary as the tires heat up. This is true, but the only places it is of real importance is in airplane tires and race car tires. Airplanes go through such a wide range of temperatures in a matter of hours that it is a benefit to them to be stable. Race cars going 175 mph can build abnormal heat and as little as 1/4 psi can affect their handling. The tires on your car or SUV are designed for pressures to increase as temperatures rise.

Here is the only exception that I am aware of at this time: Many late model vehicles (and all vehicles manufactured after September 1, 2007) must have a tire pressure monitoring system (TPMS). This is a result of the Firestone tire / Ford Explorer rollover crisis several years ago. Most of these systems have a pressure sensitive sensor inside the tire that sends a radio signal to a computer in the car to let you know when a tire is getting low. I can see where getting every bit of moisture (which is in "regular air") out of the tire may prolong the life of these sensors. I'll keep you all informed as more data comes in. A side note for a future article: These TPMS sensors will cause many routine services (tire repairs, tire rotation, etc ) to become much more complex as sensors have to be "taught" their location on the car.