I don't no shit about wheels. What does 215/40, 215/45, and 225/40 mean?
use the search function, nimrod ...
just kidding ... 215 is the width of the tire in Millimeters amd 40
is the aspect ratio which is the percentage of the width the side wall is.
so it would be 215 * .4 = 86 millimeters
So the height of the sidewall is 86 mm and the width of the tire is 215, this math is the same for all tires.
Go here for a cool tire calculator.
http://www.eunos.com/tirecalc/