NEW YORK. Hip-hop mogul Russell Simmons changed his tune yesterday after he appeared Monday with Mayor Michael Bloomberg to promote Summer Streets, a 7-mile car-less Manhattan stretch on three August Saturdays. Instead of programs for “tourists and more affluent New Yorkers,” Simmons wrote in an open letter, “we need more programs that will keep our young people from literally killing each other.” A Bloomberg spokesman responded by noting the 13 other car-free events around the city and 1,500 free events citywide for all to enjoy this summer.