Here is a brief list of tire sizes that will be close to factory size for the GD Subaru Impreza WRX and Subaru Impreza WRX STi.
Here are the applicable sizes. Each of these will work on a stock body WRX with the correct wheel/offset/suspension/alignment setup. May need fender rolling or other fender mods to fit without rubbing. 05-07 GD STi Fender mod.