I have a 2004 GMC Envoy 4WD with a clean title, 54k miles. Very good condition. I recently purchased my second set of tires, Pirelli Scorpion ATRs. They are solid and quiet, but after changing them I noticed a shimmy in the steering wheel. Turns out two were defective with high run-out, so I got some replacements for free and the same mechanic installed them. On the same visit I had a 4WD alignment and my sway bar bushings replaced. Long story short, the vibration has improved, but not totally disappeared after visiting the mechanic two more times. They are unable to detect any issues after an inspection.
The shimmy is now a subtle vibration over 60 mph and stays pretty much the same past that speed. If you let go o f the steering wheel you can see it actually shaking a bit, and the car pulls to the left. Passengers can also feel it through the seats/floor. I can't imagine the CV joints or wheel bearings are bad if the mechanic says it all checks out. If you didn't know any better it might even seem like just the nature of the car, but I've driven this car for years and I'm positive it's just not the same as before. Any insight as to what on earth is going on here?