185/60r15 on steelies VS. 175/65r14 on steelies...

[baseballfan416]

Looking to replace current tires (185/60r15 on steelies). As an alternative to just replacing the tires, I'm considering getting tires/steelies from tirerack, since it's a nominal amount more for the set. The downside is they only have 14 inch steelies.

Would moving from a 185/60r15 to a 175/65r14 have any impact on fuel economy, and if so, to what extent? I realize the smaller wheels are about 3% smaller in diameter so if they improve fuel economy is it a result of the speedometer reading faster than actual travel or is it a true improvement in spite of this?

[CTScott]

The tire width (i.e. reduced friction) would be the thing that would help with fuel economy (minimally {1-2 MPGs max} between 175 and 185). The 175s would rotate 3.3% more than the 185s, so your speedometer would be off by that much between the two.

I believe that 14" setups are typically a bit lighter than 15" setups, so you would notice a bit better acceleration (as well as the smaller diameter would also help this, but would reduce your top end / would mean higher RPMs for same vehicle speed).