2. Adjust the mirror position. If the mirror is vibrating because it is not properly aligned, adjusting its position may help. To do this, use the adjustment knob inside the car to move the mirror until it is stable.
3. Apply foam weatherstripping. Foam weatherstripping can be attached to the back of the mirror housing to help it absorb vibration. You can purchase foam weatherstripping at most hardware stores.
4. Install wind deflectors. Wind deflectors can be installed around the side mirrors to help redirect wind and reduce vibration. You can purchase wind deflectors from most auto parts stores.
5. Replace the mirror assembly. If the mirror is still vibrating after you have tried the above steps, you may need to replace the entire mirror assembly. You can purchase a new mirror assembly from a dealership or an auto parts store.