A lock arrangement for blocking the open end of a winch inlet tube of a spare wheel hoist and storage winch mounted on a vehicle frame having a bumper mounted thereon with a hole in the bumper for permitting access to the winch inlet tube, the lock arrangement including an extension tube for mounting between the hole in the bumper and the opening in the winch inlet tube and a closure for selectively blocking the open end of the extension tube including a key-actuated lock on the closure for selectively permitting removal of the closure from the second end of the extension tube to thereby permit an elongated crank member to pass through the extension tube and the winch inlet tube for actuating the winch.