I think it depends what you mean by wire cage. If the sides are wire and you have a plastic or metal tray on the bottom, then it's ok. As I understand, rats can get a condition called "Bumblefoot" if they are kept in cages with wire floors.
it depends on the cage and the situation. if the bar spacing is too large then it won't work. if the cage is a hamster cage, its too small. if the cage has a wire bottom it can be dangerous. if you live in a very drafty house then acompletely wire cage may be too drafty. if that's the case i suggest a dog carrier crate as it has solid walls but still plenty of holes for ventalation and canbe separated for easy cleaning. i will vote when i can see or at least get an in depth discription of the wire cage you have in mind.