A universal rod-to-tube adapter for mounting a rod in a tube holder, wherein the rod-to-tube adapter snugs and rotationally aligns the rod and eliminates rattle and vibration. The rod-to-tube adapter includes both a column centering collar formed as a truncated cone with a central aperture formed therethrough between its base and apex thereof and has resiliently compressible side walls, and a base centering collar formed as a cup with a cross-wise slot is formed in a base thereof, and a plurality of resiliently collapsible semi-rigid centering members extending therefrom adjacent to the base.