Was this covered under warranty for you? I'm still under warranty, but the Infiniti dealer is 60 miles from where I live so it's a hassle to get up there and checked out.

More of an update: I got an alignment yesterday. This seemed to help the problem only slightly. I can still feel the vibration right at 50-60 it starts to go away above 60, I think just muffled under engine noise, and once I get to 75 or so on the highway and sit in cruise, I can feel it more. I need to go back to the shop that did the alignment cause I still have to turn the wheel right a little to compensate for the car pulling a little left.

 

had the car into the dealer. They recommended replacing the right front bearing they said was bad. I was surprised since to me it felt like the left front was the bad one. It seems better now though so I wont complain. All fixed.

 

I assume since you took it in and had the wheels balanced and rotated, that your rims are clean of dirt and or snow. When I used to have an A4, I used to go out in the snow storms and mess around. When doing so, snow can get caught up inside the rim and really throw your balance off. But since you've had the wheels inspected, I doubt its this. I would check your control arms for excessive movement/play. Also make sure the tires are fully seated on the rim. I once broke the bead lock on a tire by sliding into a curb. There are many things that can cause vibrations and you have to eliminate them one by one. The best thing to do is to see if you have a friend and can borrow his wheels. Put all four on your car and take a drive and replace, each wheel one by one with your own.

 

I don't know if you read my post or not. I took it to the dealer and they fixed the issue by replacing a bearing. I used to have the same problem is my S4. it used to get a lot of snow it the stock wheels and the vibration from being out of balance was terrible. I took the car to a tire shop first to get the alignment and tires checked before going to the dealer. Everything looked good even the control arms. They said everything was tight.