Before directly answering the question, it is necessary to note that the vice-president role is an important one in the executive branch of the federal government, best known for being “a heartbeat away from the presidency”. If the President dies or is impeached, the vice president as the second in command takes over.
This being said, I don’t consider balancing the ticket is an acceptable method, since the President should not select a vice president just for the reason of amassing more votes. As it was noted before, this position is very important and should be considered by the President a high priority. In this sense, the vice president should be chosen knowing that he/she will be able to handle the President position if needed.