If the choice is between front or rear install, if the front ones have not been replaced, I would put them in the front.
What brand and model are they? If no amp is being used and they have lower spl sensitivity compared to the factory ones, the factory ones may be better back there.
Factory speakers I'm guessing have a solid 91-92 db sensitivity.
Our rear doors, do not deliver very good bass even with good speakers, our front doors get way more bass.