The International Cessna^® 170 Association

It might be necessary to tape some yarn-tufts onto it at 4-6" intervals and go fly it to see if/where the disturbance is. Can you stop it by slipping with rudder slightly? Are you certain it's due to the wheel pant and not a landing gear spring twist or angle? (Place tufts on the upper gearleg and look for disturbance.)
Have you had a person in the right seat confirm the right one doesn't also buffet? (Changing position from pilots seat to copilots might alter your rudder inputs and destroy the evidence.)
I don't know a specific answer, I'm just trying to brainstorm this.

I feel compelled to make a comment. Pleez, no feedback is required or solicited

So, after the yarn tufts are inplace whereever, does the pilot hang out the door and observe the flow pattern? Or does he/she turn this responsibility over to the "second-in-command?" I know, it's all done with mirrors.