Negotiators for the United Auto Workers and General Motors Co reached a tentative agreement on undisclosed terms for a new four-year labor contract, averting a threatened strike, the union said late on Sunday night. The proposed deal will now go to a council of several hundred UAW leaders from GM’s U.S. plants meeting on Wednesday, who are expected to approve it. The contract then goes to a ratification vote of the UAW’s 52,700 workers at GM.