Those are factory wheels, take a look at this link:
Stock TJ Specifications - JeepForum.com
From everything I have read on this site & another site, the biggest issue is the backspacing on the factory wheels. If you plan on going with bigger tires, then a 15x8 rim or 15x10 rim with no more than 4" of backspacing is required. You can find some deals on steel wheels/tire combos on the web.