You should check the width of your rims. It should say somewhere on the rim, but you'd have to take it off the car to find it. Or you could look it up. I'm sure you could put 215's on there or even 225's, but keep in mind that the profile "40" is the aspect ratio, and it changes with the tread width. If you went with much wider tires, you would probably want a sidewall that is 35 percent of the treadwidth, so the diameter isn't too big.
Here's your site:
www.tirerack.com. Search for tires by size and performance category, and when you've found them, click on their SPECS. The outer diameter for each size is listed, as well as the range of rim width they're able to fit.
Dan