Use the calculator to see what happens to your speedometer reading when you change the size of your tires and wheels. The graphic shows your stock tire selection in an outline overlaid on your new tire selection.
It does not have info on offset but will show you dimensions of a new tire/wheel setup comapred to stock setup.
P.S. this site is not specifically for miatas, it applies to all vehicles.
Brad
Playerseightball@aol.com<ul><li><a href="http://www.miata.net/garage/tirecalc.html">http://www.miata.net/garage/tirecalc.html</a</li></ul>

<ul><li><a href="http://www.c5-corvette.com/tirecalc.htm">http://www.c5-corvette.com/tirecalc.htm</a</li></ul>

<center><img src="http://pictureposter.audiworld.com/14894/partyaudi.jpg"></center><p>

http://www.fernblatt.com/longhurst/tyre_bible.html<ul><li><a href="http://www.fernblatt.com/longhurst/tyre_bible.html">http://www.fernblatt.com/longhurst/tyre_bible.html</a</li></ul>