Fill your tires. Reduce your CO2.

So I know we've got this wiki on maximizing your fuel economy with traditional fuels as well as this one for hybrid vehicles.  But this is a pretty crazy statistic from AutoblogGreen:

Incorrect tire pressure is responsible for the production of an additional 18.4 metric tons of CO₂ which end up in the atmosphere each year. This is one of the findings in a report by the FIA (International Automobile Federation) and Bridgestone partnership. We can translate the figure in to wasted fuel as well: about 8 billion liters of fuel wasted per year. Moreover, 55 million tires per year are thrown away because of premature wear and tear due to incorrect pressure. For instance, when running at 90 km/h (60 mph) a car with tire pressure that is 1 bar below the recommended figure burns from one to three percent more fuel.

WHAH?!?! That is mind-blowing. Seriously. I'll be right back, I gotta go to the gas station.

 Thank you for bringing this point up!

Proper inflation of your cars tires means your tire is realizing the proper shape that is optimum for the operation of the vehicle.  Under inflated tires act an extra source of friction and requires the engine to work harder in order to keep the vehicle in motion or to start up from stop.  Under inflated tires, since they produce more friction, heat to a higher temperature and cause premature wear of the tire material.  Additionally, since they are under inflated, they are not shaped properly for the vehicle and will assume the stereotypical flat-bottomed circle appearance.  This extra tread patch means the tread, and possibly part of the side-wall, are in contact with the road-bed, increase the physical wear on the tire.


All-in-all, under inflated tires cost you lots more in the long run due to decreased tire life and decreased MPG.  Properly inflating your tires is not only good for the environment, but safer for the vehicle occupants and your wallet.  

Now, if you want to get into some really esoteric discussions on tire pressure as relating to vehicle MPG, then you can send me a PM.  I've read some interesting points on the hybrid forums....