It's well established that wider= lower rolling res.
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One reason is that a larger diameter tire will 'bridge' across unevenness of the road better.
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Same can be said for wider. You can look at the Cummins data for rough vs smooth roads. A narrow, high pressure tyre is a bit like bringing a rough road with you everywhere you go.
If we want to explore rolling res you can look at bike racing. On an indoor velodrome (wood boards) you'll see them running 19mm tyres at ~150psi (220 is max side wall!).
Road racers used to run 23mm at ~120psi, but since new data has come in, most pros now run 25mm at ~90psi. 28mm at 70psi offers lower rolling resistance still, but 25mm is seen as the best compromise between res and aero drag.
Thing is we all 'knew' that higher pressures were 'faster'. That's how it 'feels' and 100% of riders 'know' that. Now dyno and wind tunnel testing have shown those seat of the pants instincts to be mistaken.
In short, if you have particularly rough roads you may have better results in a more compliant, wider tyre running at a sensible pressure, if you drive on polished concrete go narrow and pump it up till they bulge!
Now having said all that, if you look at Metro's chart, I think you'd be silly to fit wider tyres chasing RR if they throw your Cd out. Those Cd gains are massive -especially as they also reduce CdA.