I went thru the first 10 pages of the sticky and not 1 balt sedan.

Also, I want to get 18s, but im not sure about the tire size.

Tirerack.com suggested 215-40-18, but alot of users here have many different sizes, ex. 225-35-18

Here you go: 18x7.5 with 225/40/18. Thats the widest tire you 'can' put on a 7.5 wide rim. If you call tire rack up there actually knowledeable and will let you know what can be done because the offset of the rim is also going to make a differene.

225/35/18 is what they might recommend because 225/40/18 is a slight bit taller than the stock size (depending on the actual tire brand and model. They have the overall heights of the tires on the website and thats what I went by when choosing my tires) but its hardly noticeable on the speedometer; it was probable less than 1MPH.

http://img383.imageshack.us/img383/6914/picture035as9.jpg