The statement is "reduces tire drag". The tire drag coefficient is reduced by 15% and the math works. Tire pressure is increased by 12%, re-check your figures.
Got a life!!
Bob
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2009 Corolla S. My Car
2009 Camry Hybrid, Wife's :
2008 Harley Davidson Screaming Eagle Road King-My Bike
2005 Harley Davidson Deluxe-Wife's Bike
1998 Honda Accord EX (Daughters, but I bought it)
Photos located at
http://community.webshots.com/user/currybob