If it's not a tire problem,
And it's not a tire inflation problem,
And it's not an alignment problem (caster, camber, toe),
And it's not a suspension part that is injured or bent,
And it's not a brake problem (something dragging), (don't neglect to check the rear brakes too!),
Then it could be a bearing problem,
Or it could be related to the power steering system (the valve is sticking, or something is worn or injured).
-General automotive mechanic since 1972