I know the question was for Wayne but may I be so bold?

The reason for the higher pressure is for a harder tire, which reduces rolling resistance.
Sort of like:
It is harder to pedal a bicycle on the soft sandy beach than on a sidewalk.
Same number of rotations, but you are sunk in the sand.
Same with walking on soft, shifty sand, or knee deep water: much better on the boardwalk.

If your bicycle tires are rated for 60lb max pressure and you only have 40,
it is harder to pedal on the soft, shifting rubber.

Efficient drivers do it better.
1003 miles a tank personal record. 74MPG calculated. HCH1 CVT