Every cloud has a silver lining. You have earlier mentioned in one of your questions that you are feet loving person and want to play with your wife’s feet. Feet fetish is very common fetish and nothing wrong herein but your wife’s reaction depends on her information concerning fetish. If she is familiar with feet fetish than, I think you have no problem in disclosing your fetish to her. Be prepared to listen no, as it is her right to say no. You cannot compel your wife to cooperate with you if she is not comfortable.
You can do one thing, make a plan to see porno movies with your wife and bring movies in which foot fetish is key part. Try to chat about running scene with your wife, this way you can recognize her philosophy on feet fetish. If she shows any affirmative sign than ask her that you will love to try it. Go slowly and make her comfortable, I am sure you will live your fetish but you have to go by root.
Let us know your success. Best of luck