Originally Posted by Murrays

Narrow tires have less rubber and therefore weigh less so you will have better acceleration and hill climbing.

Narrow tires actually have a HIGHER rolling resistance than wider tires at a given pressure. This is due to the fact that a narrow tire must deflect more to get the same contact patch vs. a wider tire (contact patch = weight on tire/pressure in tire). Since rolling resistance comes from tire deflection, narrow tires take more energy to move.

Of course, you can counteract the higher rolling resistance with higher pressure, but you’ll have a rougher ride. Besides that, you can probably add another 10-20 psi to your existing tires without any problems.

See Sheldon Brown under “Width & Pressure” http://www.sheldonbrown.com/tires.html#width

-murray