[RedDevil]

As the tire is a bit narrower it would have slightly less aerodynamic resistance and less weight.

But most effect will come from the sidewall height.
Every tire flexes where it hist the road, and the higher the sidewall is, the easier it can accomodate the flexing.
Bigger rims mean you need a smaller sidewall on the tire to keep the same circumference. Big diameter rims mean small sidewalls, so high flexing and rolling resistance.

I run 40+ PSI in my tires; the sidewalls hardly bulge, much less than at 34 PSI or whatever Honda recommends. It is also less sensitive to sidewind and corners better.

Just changed my Turanza 185/55/16 summer tires on alloys for WinterContact 175/65/15 winter tires on steelies; run both at the same pressure, hardly any difference between them in economy and handling, except when it rains or snows

PS take a look at:
http://ecomodder.com/forum/showthrea...els-23509.html