Originally Posted by FBinNY

I'm not a fan of ultra narrow tires on wider rims not made for them. This isn't to say they won't fit or hold air, but with a correctly matched tire/rim combination, the tire will assume an Omega profile with the tire widest halfway up, and pinched back at the rim. This provides a nice flex zone and ensures the tire handles as designed. If the rim is too wide, the tie has an inverted U profile, and it's vertical flexing suffers, causing reduced traction on bumpy roads.

My guideline is that the tire width should be one and a half times the rim's inside width or more. There's fudge room so close is OK.

As for rolling efficiency, the narrower tire may roll easier than the wider one depending on tread, but IMO might be too far to the other extreme. Consider a 1.5 or 1.6" wide tire for better balance in handling characteristics.