Constant driving vibration noticeable over 40mph

Given your tire wear, it sounds like an alignment.

Are the wheels balanced?

Did you check for play in tie rod ends and ball joints when you did the wheel bearings and noticed bad boots? You can do that with large channellocks and a pry bar.

Good luck.

 

Always check for rogue lead weights that could have found their way inside the tire when it was fitted. I had that once and it was a nightmare to track and trace. When the wheel was fitted on their balancing machine the weight stayed in one place so giving impression wheel was balanced. When fitted on the car it would bounce around inside the tyre causing vibrations. "But we've checked that wheel twice - there's nothing wrong with it", when there was.

First thing I always check now if having strange vibrating wheels.

 

Bad tyre? (…broken belt in the tyre?) I've seen that on the rear offside wheel of friend's Audi, thought at first it was a bad bearing but it was a tyre with a broken belt)

 

I had bad rear bushings that caused vibration. More likely your tires. You have a shifted belt.

 

You can check your rotor's trueness with a dial indicator with magnetic base. Also good to check them with a micrometer too.

3rd gen rotor specs are in the attachment, but they should be in the ball park:

 

Sometimes wheels don't need a weight. Can you see a spot on the rim where there obviously was a weight, some crud residue? If you're just seeing a wheel without a weight, but there's no such obvious evidence there was a weight, I'd first get the balance checked.