2005 Pontiac Vibe (only owner) 61K miles began vibrating at HIGH SPEEDS ONLY through steering wheel and throughout front end. The vibrating is not constant and happens sparatically but again only at high speeds 65+. When breaking at high speeds I could also feel the vibration in the steering wheel. As the vibration worsened I began to hear a sort of knocking/thumping during the vibrations. Tires were purchased in 2011 and rotors purchased maybe in 2010/2011 as well. SO In Sept 2013 i took my car to a mechanic, he drove the car and thought the rotors needed turning and balanced the tires. After that job my car seemed to have improved! After a 700mile trip the vibrations were back. I took my car to a different mechanic who recommend 4 new tires (but his shop specialized in tires). I was skeptical so I went back to the mechanic I had seen in Sept for his diagnosis. He too recommended 4 new tires but his shop did not purchase or install tires so he recommended I go to a tire specializing in tires. I then took my car to a discount tire where the guy confirmed uneven wear and showed a bumpy tire, SO i broke down and $500 late have 4 new tires. Here it is 2 days later and the vibrations and thumping are back!!! ARGHHHH! Someone please please please have some helpful suggestions! I am not sure where to go from here and tired of putting more and more money into this mystery vibration.
I would suspect a bad axle, on the side where you were shown the bumpy tire.
The vibration might be caused by tire bounce because the front struts are worn.
Tire bounce occurs when a spinning tire reaches a certain frequency where the worn strut can no longer hold the tire to the road. And the tire starts bouncing.
You can see an example of tire bounce on Youtube.
For this type of problem, I suggest that you have a knowledgeable friend follow you in their vehicle and observe your front tires when the vibration occurs. For safety purposes, you will want to use a divided highway when it is not busy.
As an alternative, have someone else drive your vehicle and you follow in another vehicle and observe for yourself.
Bent rim(s) caused at the time old tires were dismounted
crud or corrosion between the rim and the rotor
crud or corrosion between the rotor and the hub