If a file a Chapter 13 and my wife is on a loan, does she need to file as well?

She does if she wants to have her liability for that debt discharged (eliminated) in that bankruptcy case.

It is preferable for both spouses to file together.  Unless she has debts that she does not want to have included in the bankruptcy, it would be beneficial to clear the debt for both of you.  If the debt is joint, she would then become liable for any portion you do not pay.  You may be defeating the purpose of filing the bankruptcy if your "family" finances are not left in a better postition at the end.

Since it is a Chapter 13, and if it is a secured debt that will be paid in full, she does not need to file.  Your question is loaded and there are a great deal of "if" "then" scenarios that could occur.