Here is a link to a wheel site that gives you ll kinds of fitment info. Such as bolt pattern, offset, tires sugestions and all kinds of other stuff. Check it out if for nothing else than the technical info.
http://www.bigwheels.net/index.php
And here is a tire size caluculator to figure out what will fit closest to your stock tires nd how much your speedo will be off.
http://www.miata.net/garage/tirecalc.html