Well, this is all preference, but here is my 2 cents: First of all, I assume you will be running in STX based on your wheel choice (7.5" wide). STX means that you will be running DOT tires, not R-Compound tires. With a 225/45 tire, you will be running a slightly taller sidewall. This (combined...
Please be very careful doing this, as the lower the tire pressure the more likely of rolling to the sidewall and possibly onto the rim. Running a lower pressure can be helpful for traction on the front, but without proper camber (which a stock 9th civic does not have) I wouldn't go that low and...