Tire Size question?

[I ask good questions]

When putting s14 wheels on an s13 do I use the same tire height as stock on the s14? If not what tire height do i need to keep the stock gear ratio? Also should I run 215/55/16 or 225/55/16 if I keep the height the same?

[94_240sx]

This site a great site when you try to figure out something like this.

http://www.miata.net/garage/tirecalc.html

[nismofly]

use the same size, 205/55/16

and the middle number is not a direct measurement, its the sidewall height as a percentage of the width of the tire