Originally Posted by Wildwood

edit: my comments below really are about where I thought this was going, but hasn't.
To the tire pressure ratings on the sidewalls of your tires, they should only be relevant to a new rider or a low pressure tire like on a vintage hookless rim, or maybe on a kid's bike. Once you ride the bike/tires you should know where your preferred inflation range sits. If you ride at MAX pressure, you have probably done this before. There is no single ideal pressure, given all the variables.
______________________ I find all this talk about wide tires at low pressure giving the lowest rolling resistance a bunch of confusion.
The rolling resistance of a tire can only be measured on pavement or very hardpacked surfaces. On gravel, the rider who picks the best 'line' will have the most efficient forward motion.

Originally, the tests of real world rolling resistance proved that going from a 23mm to a 25mm to a 28mm at equivalent pressure, reduced the road surface contact patch, thereby lowering rolling resistance. Then the conversation went toward comfort and by lowering the tire pressure in a 25 or 28 so that the contact patch equaled a 23mm tire, the rolling resistance was the same but slightly more compliant and perceived as more comfortable. From that point the conversation devolved. To the ridiculous statements like - "on my 50mm tires at 25psi, I'm faster than on 35s at 60psi, and the rolling resistance must be better because I feel less beat up at the end of my ride." Jan & Grant espouse a particular type of cycling and both make their livelihood from the products they sell into that cycling niche. Fat tires and low PSI have a place in cycling; they are great for off-road, loaded touring, cargo bikes, mountain biking, etc. Tires with lighter sidewalls make a smoother softer ride. But the hyperbole about fat&soft having lower rolling resistance than narrower and harder needs to be taken as 'alternative facts', otherwise known as bullpucky.
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