Chairman of Tata Group Ratan Tata has said he plans to retire but has not identified his successor yet.Asked whether he plans to retire at some point, Tata told the New York Times in an interview yesterday that he has plans but his successor has not yet been identified."I'd like to retire when I can still walk and play golf and fly and do all the things that I like to do," the 68-year old chairman of the Tata Group said.