Larger tire diameter for increased mpg?

[CapriRacer]

A word of caution:

If you are going to test the difference tire diameter has on fuel economy, then it is important that you eliminate as many variables as possible.

Specifically, a new tire will have more rolling resistance than a worn out tire - all other things being equal.

Also, differences in rolling resistance between tires - even those of the same size - can be HUGE!

But as a general rule, larger diameter tires will have ever so slightly better rolling resistance - all other things being equal.

[MPG101EES]

It has been our experience that a taller tire and a narrow tire properly inflated or slightly above will give you some fuel economy improvement. We have always noticed that the taller tire will turn down your rpms. If you are really into things, you can also look into changing gear ratios.