Two aphorisms to live by when dealing with car repairs, both enshrined by Ron Ananian:
- NEW means Never Ever Worked. NEW doesn't mean GOOD.
- Diagnose, diagnose, diagnose. Then repair.
You need a better mechanic. One whose diagnostic repertoire is not limited to educated guessing and throwing parts at a problem and hoping they fix it. But you have to be willing to pay for diagnosis -- as much diagnosis as it takes for the mechanic to know for sure that the repair will fix the problem. A competent diagnostic mechanic should be willing to state that if you give them leeway to perform a full diagnosis and pay for it, they will guarantee that the repair will solve your problem. Anything less and you're dealing with a parts-changer. So pose that question when you interview a new mechanic: Will you guarantee that after diagnosis and repair, my problem will be fixed or it's on you? You may end up spending more for repairs by such a mechanic, but you won't be going back again and again for the same issue.
Regarding your vibration: A new bearing can be bad. Brand new tires can be defective. Wheels said to be balanced can be poorly balanced. So assume nothing.
It's easy to find out if it's the wheels / tires or not, so you have a starting point. And if you can change a tire, it will cost you nothing. Put the front tires on the rear and the rear on the front. (Keep left on left and right on right.) Take it for a test drive. If the vibration is gone, there was something wrong with a front tire. If you can still sense a vibration but not in the steering wheel, there was something wrong with a front tire. If the vibration in the steering wheel is exactly the same, the tires or wheels are not the cause.
If the above indicates that it's a tire or wheel problem, then once again swap the tires either on the left or right side, not both. The change or lack of change will tell you which side is bad.
Some of the possible causes of vibration in the steering wheel at a specific speed:
- One or more tires is out of balance or has defective belts
- One or more wheels is out of round due to impact
- One or more alloy wheels has been warped by over-torquing the lugs
with an air impact wrench
- Bad wheel bearing
- Bad CV joint
- Bad half-shaft
- Bad steering damper
- Worn struts / shocks
- Worn ball joints
- Worn tie rod ends
- Worn steering rack or steering box
- Worn rubber bushings
Each of the above (and more) has a specific diagnostic procedure that is easily performed by a competent mechanic. An experienced mechanic will know what to check first to repair your car as expediently as possible, if you're willing to pay for diagnosis.