Originally Posted by
ClydeClydeson
All other things being equal, wider tires have similar or less rolling resistance caused by flex in the casing.
All other things being equal, wider tires are a bit heavier than the same tire in a narrower width.
The big assumption here is that all other things are equal. Once you start looking carefully, most (not all) tire models start picking up sidewall stiffness as the width increases, usually between 25 and 32 mm wide. That's why tires wider than 25 or so often have higher rolling resistance than narrower tires. The exceptions are usually pricey.
Many road bikes older than five years are limited as to the size tire they'll take, often maxing out at 25. In that case, ride the widest tire that'll fit. Otherwise, you'll have to try a few and pick your own optimum combination of width, ride, price, and puncture resistance.