2000 Cadillac Deville right front tire vibration

I have had a problem with the right front tire vibration, a year ago I suspected it was the rotors, so had these changed and that corrected the problem. The old rotor was warped although I do not do heavy towing, braking or drving. Since then the problem has come back. I had new tires put on a few days ago and did not notice any improvement. Do you know if there is anything more I should have checked out?