This sounds like a lot of hot air to me.
For example: tire pressure make no difference in fuel economy? Try this test; Inflate your bicycle tire 10 PSI below the recomended inflation pressure and go for a ride. Then inflate as recomended and go for a ride. Which ride took less energy?
-- Dan Meyer
So if I go from 100# to 90# I would notice a difference? Actually I don't own a bicycle anymore so I'm working from memory here.
I did see this at another automotive site: "Under-inflated tires
can lower gas mileage by 0.4 percent for every 1 psi (pounds per square inch) drop in pressure of all four tires
. " So a 5 psi reduction (in all four tires!) would be 2 percent lower mileage or if you normally get 20MPG you would get 19.6MPG. Somewhat confirms the finding of minimal difference, IMHO. http://www.carcare.org/Tires_Wheels/inflation.shtml