My bike, the Kona Big Rove AL, came stock with Schwalbe Big Apple tires. The Big Apples are lined with Kevlar for puncture resistance, and they weigh about two pounds apiece. For the least rolling resistance, Schwalbe recommends about 50 PSI, but about 45 PSI for protection, durability, and grip.
Collective wisdom, not to mention many people on group rides I've been on, says that wider tires = more rolling resistance. Schwalbe refutes this with this quote:
"The wider the tire, the lower the rolling resistance. Because a wide tire has a shorter footprint in the driving direction, the tire bounces less and the flattening of the footprint on the road is smaller", explained Frank Bohle. Result: The tire deforms less, remains "rounder" and rolls more easily.
Frank Bohle, the guy they're quoting here, is one of the company's founders. If that makes you take his statement with a grain of salt, so be it.
Jan Heine, the editor of Bicycle Quarterly, has a somewhat different take on the "wider tires roll better" viewpoint. He believes (I'm paraphrasing) that "wide, supple tires" roll better. Mr. Heine is also one of the owners of Compass Cycles, who sell tires; so he has, as they say, a dog in this fight.
Well, the Big Apples are wide, but supple they are not. Probably something to do with the Kevlar lining. They're great for bike commuting through refuse-laden city streets. But for faster group rides, not so much. So for the sake of a fast group ride I went with thinner tires; Panaracer Paselas. At 75 PSI/35mm they rolled really well. But for comfort...well, I could've done better. Even dropping them to 70 PSI didn't noticeably increase the comfort level.
The Big Apples go back on. The comfort level goes back up.
And the search for the perfect roll goes on.