Anyone getting 60+ mpg on tires other than Integrity?

[patsparks]

Skinnier tyres reduce drag as well as other factors but you have higher sidewalls than stock which mean your odometer will read less miles than they would if you had stock tyres because the wheels turn less times per mile than stock. They also mean you need more throttle to achieve the same acceleration. Try this tool http://www.miata.net/garage/tirecalc.html
It will tell you about changes to tyre radius with changes to tread width and aspect ratio.

[drees]

Yep, as patsparks says, there are a number of things to watch out for when changing tire size:

• Going with a bigger tire (in diameter/circumference) will decrease acceleration and gas mileage as it will be heavier and have more rolling resistance.
• Going with a bigger tire will also make your odometer/spedometer read low. This will also cause your mileage to appear lower than it really is.

Note that when going with a wider tire, unless you change the aspect ratio the tire will also be taller. For example, when you switch from a 185/65/14 to a 205/65/14, not only does the width of the tire increase by 20mm, but the circumference increases by 3-4%.

The tire size calculator will let you know what tire sizes maintain the overall circumference as stock which will keep the speedo accurate.

And yes, in general, smaller, narrower tires will be more efficient than larger, wider tires.