there is a massive amount of discussion on different factory wheels for different vehicles that fit the Sportage as well as a massive amount of discussion about what fits and what don't. use the search function to give you some ideas.

anything with a 5-5.5" bolt pattern will fit. period. offset means nothing. backspacing is more a matter of how much you want the tires to stick out as far as LOOKS go. if you don't want a 30-31" tire to rub with no lift, then get somethign close to stock backspace, but other than that, you don't need all that information. just TELL them what you want. if they say they can't do it, walk.