Greetings,
All you folks that "over" inflate your tires: are you driving primarily at highway speeds, or are you staying below, say 40mph most of the time? Just curious.
The reason I'm asking is that if you are driving primarily at highway speeds, then aero drag swamps any gains due to reduced rolling resistance. And as measured by
MetroMPG, there is about a 10% gain to be had to go from normal(ish) pressure up to the sidewall max, and about another 3% by going above this -- but nothing is gained by going more than 6psi above the sidewall max.
As we all know aero drag goes up by the square of the speed, so:
30mph = 900
40mph = 1600 (almost 2X 30mph)
50mph = 2500 (almost 3X 30mph)
55mph = 3025 (3.3X 30mph)
60mph = 3600 (4X 30mph)
65mph = 4225
75mph = 5625 (6.25X 30mph & more than 2X 50mph)
I've got to think that a 10-13% gain is swamped by the drag, even at just 40mph?