Tires: tires/gas mileage, worn tires, auto tires

Question
Do narrower width auto tires get better gas mileage than wider widths, (a lot, so-so, much better)

Answer
Larry,

As a general rule, the heavier the tire, especially weight in the tread area, the worse the fuel economy.  That would be that narrower tires would be worse than wide tires.

BUT!!!!

There can be enough difference between tires that comparing individual sets of tires would result in a reversal.

AND!!!

This also means that worn tires get better fuel economy than new tires (if everything else remains the same).

PLUS!!!

Inflation pressure has more effect on fuel economy that differences between tires.

FURTHER!!

Tires that give good fuel economy don't wear as well, so you'll be replacing tires more often and the net effect is that overall it costs more to use tires with good fuel economy.  

MY OPINION!!!

You should stick to the original tire size,  use 3 to 5 psi more than the vehicle manufacturer's recommendation for pressure and select tires with good wear numbers (keeping in mind that the traction values and speed ratings are important for safety reasons.)