I HAVE A HARD SHIMMY IN RIGHT FRONT WHEN I HIT A CHUGHOLE AT 65 OR MORE MPH
About the only thing to do would be to inspect it. Put the front end up on jack stands and start looking. Look for loose mountings and or play in the joints.
Most common if it was not there until you hit the chughole would be a busted belt in the tire. You can rotate the tire tot he back and see if it changes. Replacing the tire would be the correct measure to take.