Thanks...that's a good calculator.

You have already received some good advice; The following may help you with
your decision. Gear ratio's (tire and wheel size) directly effect your
milage and acceleration.  I personally try to keep the same overall gear
ratio that the manufacture designed the car with. It's usually the best
combination of milage and performance.  Go to www.miata.net/garage  click
on wheels and tires, click on tire size calculator on right. Good Luck

Whoever installs the new wheels should be able to find a tire rim
combination that has the same outside diameter as the original.

I question whether alloy rims would be mnoticeably heavier than the
original steel rims.

Elliot Richmond
Freelance Science Writer and Editor

you may never again know what your mileage is since the larger wheels
will cause your speedometer and odometer to read low.

    Hey.... I got a 2002 Civic LX 5sp with stock 14" steel wheels and
hubcaps. Right now I do a lot of commuting and get about 39 to 42 miles per
gallon. However don't like the looks of the cheap looking hubcaps on my
Civic and was thinking of going to the nicer looking 15" or 16" Honda wheels
or nice after market wheels.

     But, I really don't want to lose my good gas mileage that I'm getting
with my Civic.

     I did some checking and my stock steel wheels, plus tires and hubcap
weight around 31 pounds. going to a new larger wheel and tire will add
around 10 to 15 pounds per wheel and tire.
     I do a lot of atv riding and no first hand at the power you will lose
by getting a heavier bigger wheel and tire, so was wondering about the mpg
that all Honda owners here have experienced when they install new sets of
rims. Thanks for any advice, Rob.