A tie-down apparatus includes a frame, a reel, a coils spring and a strap-replacing tool. The reel is supported on the frame. The coil spring includes an end connected to the frame and another end connected to the reel. The strap-replacing tool for gear includes a gear and a pawl. The gear is connected to the reel at an end and formed with teeth on a periphery. The is pawl engaged with the teeth of the gear so that the pawl prevents the gear from rotation in a first sense of direction and that the pawl allows the gear to spin in a second sense of direction opposite to the first sense of direction. The pawl keeps the gear in position against torque provided from the coil spring via the reel that tends to rotate the gear in the first sense of direction.