Originally Posted by jschmid

Actually the second number is not a measurement of sidewall height, but rather an aspect ratio of width to sidewall. For example a 225/45 tire will have a taller sidewall than a 225/40 tire. That's why when you see lambos with 335/30/18, they still have plenty of sidewall height.

For 6th gen, 225/45/17 is actually the EXACT same rolling diameter as the stock 4cyl tires.

225 is also about the widest you'll want to because of rubbing issues.

Use a tire calculator to check out possible tire sizes.

215/45 or 205/50 are other options you could use as well.