nitrogen is used to leak check refrigeration systems because it contains no moisture. as any A/C tech knows, moisture and Freon = corrosive acid and a ticking time bomb. but that's besides the point. unfortunately my impression of using nitrogen in car tires is a cute idea but basically pointless if you're just driving around town. yes nitrogen will remain at a more consistent pressure during temperature fluctuation due to the lack of moisture, but even severely humid air in your tires will only allow for a couple PSI swing and that's worst case scenario. as for holding air longer...the claims are that nitrogen molecules are larger than oxygen molecules and therefore will not dissipate through the rubber as quickly...well maybe but the rate at which tires might naturally deflate is so slow to begin with you would surely see a service bay with a tire rotation before it ever became an issue...and it's never really been proven it's just a claim with a little science to back it up. what you definitely do gain is green valve stem caps tho...sweeeet