Let them know you want to change the nature of your relationship with them from child to adult. Keep this focus the foundation of your discussion. Address the issues you discuss with your wife. Be specific about the behaviors you want changed, but keep this part short. By setting the framework for your discussion about you and your needs for a change in how you relate to them you are more likely to create the necessary shift that is no doubt at the root of this transition.
Marriage is the blending of two family cultures.
It is your job to take the lead in determining the rules and guidelines with your wife that you will create together in you family. It is possible that one of the reasons for your lack of leadership with your parents is that you are avoiding your own conflicts with your wife, allowing your parents to express your own desires. Whatever your reason for avoiding conflict, this pattern could spell trouble for the future of your marriage. Conflict-avoidance can lead to unresolved feelings which result in a fractured relationship. You may need to strengthen your communication skills not only to address your parents, but to maintain a healthy and vibrant marriage.