I love it when "physicists" are asked questions on BFN. The more "physicists" who respond, the more different answers one gets!

I would rephrase the question a bit:

If 120 or 110 psi is good for a 700x25 or 23, why isn't it good for a 700x38? Especially when research (by physicists?) show that larger tires with more pressure have less rolling resistance, generally.