[Sugarphreak]

True, when using max tire sidewall pressure blow outs are not a concern. Also there is some safety and comfort margin in the reccomended PSI of probably a couple of pounds.

However the tire is designed to be running with more weight at that pressure as it is a intended to fit a wide variety of vehicals. A giant heavy domestic car running the same tire will probably have a higher reccomended pressure. With that amount of pressure in the tire for a vehical which only reccomends 32psi you are without question not providing enough force downward to counteract the outward deflection that would naturally occur.

When it comes right down to it there is really no other way to explain why you get better MPG using higher pressures other than you are reducing surface area. Using that logic, if you reduce the surface area the points of contact will have more weight on them and will wear faster.

In this case we are seeing roughly a 9% increase in overall efficency. If we assume this directly relates to the tires then that is a 9% reduction of contact on the flat tread (highway's don't exactly roll the tire on corners so we can dismiss any rolling resitance along the side tread). With 9% less contact your wheels we can only assume the deflecting tire is also arching out to create that affect and has an substatial increase in weight right along the center that would not normally be there. So really the wear in the center of the tire would be somwhere between 10%-20% worse than a properly infalted tire.