Tire Pressure Cost me! - Toyota Yaris Forums

sbergman27 · 03-05-2010, 10:33 PM

The general rule of thumb, based upon Goodyear's testing, is about 0.3% decreased fuel economy for every 1 psi *below* the number recommended by the auto manufacturer. So if all four tires are low by 5 psi, one might expect to see about a 1.5% decrease in fuel economy. Presumably, this is for combined mpg. The difference would likely be lower for highway, and higher for city, since wind resistance dominates the highway mpg figures. And I would expect to see diminishing returns as one goes *above* the recommended pressure.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Higher Tire Pressure	captainm27	General Yaris / Vitz Discussion	46	01-27-2009 11:17 AM
The Tire inflation debate...	Tankota	General Yaris / Vitz Discussion	20	06-01-2006 08:09 PM

03-05-2010, 10:33 PM	#17
sbergman27 Drives: 2008 Yaris Sedan Join Date: Feb 2010 Location: Oklahoma City, OK Posts: 323	The general rule of thumb, based upon Goodyear's testing, is about 0.3% decreased fuel economy for every 1 psi below the number recommended by the auto manufacturer. So if all four tires are low by 5 psi, one might expect to see about a 1.5% decrease in fuel economy. Presumably, this is for combined mpg. The difference would likely be lower for highway, and higher for city, since wind resistance dominates the highway mpg figures. And I would expect to see diminishing returns as one goes above the recommended pressure.