Time Warner Inc. has nominated four new directors, expanding the board to 15 members from 11.The nominees — Carla Hills, David Kearns, Reuben Mark and Fay Vincent — will stand for election at Time Warner’s annual shareholders meeting on May 20. “These are real quality independent people,” said Emanuel Gerard, of New York investment bankers Gerard Klauer Mattison & Co. “This is an essential turnover of the board. You had a company with Calpers (California Public Employees Retirement Fund) and big institutions on their back, and they put a lot of outsiders on the board. It’s basically a very healthy development, long-term.” A company spokesman said that when Time Inc. and Warner Communication merged Jan. 10, 1990, the combined board consisted of 24 members. Hills, 59, served as U.S. Trade Representative from 1989-93. Among other government posts was a stint as Secretary of the Dept. of Housing & Urban Development in the Ford administration. Kearns, 62, is the retired chairman and chief executive of Xerox. A director of Time Warner from 1978-91, he gave up his seat to serve as Deputy Secretary of Education in the Bush administration. Mark, 54, is chairman and chief executive of Colgate-Palmolive. Vincent, 54, served as the eighth commissioner of Major League Baseball. He was also chairman and chief executive of Columbia Pictures Industries Inc.