I have a 2006 GS300 RWD w/55k on the odometer.

Lately I've noticed a distinct rumbling/vibration that you can feel
through the gas pedal or the steering wheel.

Symptoms:

- Regular city driving it isn't noticeable.

- When driving on the highway, starting at approximately 55mph, the
vibration can be felt through the gas pedal and steering wheel and
slightly audible via the ears.

- When driving at said speeds, when turning the steering wheel to the
left slightly it goes away altogether, but becomes more pronounced
when turning to the right.

- The odd thing is, even when the steering wheel is turned to the
right slightly, the vibration isn't constant but every, say 50
rotations of the wheel/tires.

Any suggestions before I take it in? Bad wheel bearings, shock/s?

 

When was the last time you had the tires balanced?
If it's been awhile, you can try that first and see if the highway speed vibrations go away.

 

I've tried 3 different sets of wheels/tires including the stock wheels in the last 2 months and the problem persists.

 

Anyone else with any suggestions?

Doing some research here, it looks like it may be the front passenger side bearings?

 

Could need either a high-speed wheel balance or maybe one of your rims is bent. It happend to me when I had my 430 and I had to get the rim fixed. The mileage is kind of low for wheel bearing but that would be my last guess.