Black wrote:15's are good size rims, as the smaller the rims the more acceleration you get just a less top speed.
WTF?
you can change the rim size and not effect the acceleration or top speed... as long as you keep the rotational circumference the same it is all the same.
however... if you do change the rotational circumference it will make a bit of difference to things.
check out here for a handy little calculator.
http://www.miata.net/garage/tirecalc.html
If you do go for bigger rims, make sure that they don't weigh a ton and a half, as that will have more impact on acceleration/top speed on a small car. Also it will make a difference to braking as well.
I recently had a set of 19" ROH somethings(mate was selling them from his trailer... 19's, on a trailer
) on the front of my car, and kept triggering the ABS when I was breaking no harder than usual(I had never hit the ABS trigger point prior to this)... put my old wheels back on, and it was fine again, it made more of a difference than I even thought it would.