How big of tires and wheels can I put on my car?
 

Corolla S, it currently has stock wheels/tires 205/r 14 or something close to that...I was wondering if Its okay to put new 15" rims and tires on it just to make it look better, Im not concerned with gas mileage.

Corolla S is a very famous car and if you want to modifies it by changing its tyre then you just go for it. I think tires 205/r 14 can be easily replace with 15" rims. After doing this, it looks great.

I got a set of Uniroyal Touring Trak A/S's from SimpleTire.com and have been really happy with them. Pretty sure they'll have them in the size you need, and the price is pretty hard to beat.