What's causing this noise/vibration?

My car is a 2011 Prius II ~100k miles (not the plug-in). Last fall I had snow tires installed just before winter. I had an alignment done at the same time. Now I've had my all season tires placed back on the stock wheels. These tires are the ones that were on before I had the new snow tires put on, so they are used. Also, since they were on before the alignment, there is some uneven wear on the inside of what is now the rear passenger-side tire. I notice that there is some vibration when driving, and I don't know if its because of the tires, or the brakes. There is a pulsation in the brake pedal when braking, but there is also a vibration felt in the gas pedal, and there is some noise too. The sound occurs even when the IC engine is off and I'm rolling down a hill, etc. so I doubt it's the engine. What I think is the noise is from the tires, the pulsing brakes it just worn brakes, but I don't know why there is a vibration feeling without the brakes depressed? What about wheel bearings?

On a side note, the issue is with the rear brakes only. I've replaced rotors and pads last year, and the noticed that the slide pins were rusty and dry, so I cleaned them up and put some SilGlide on them. I made sure the calipers could slide in and out but now a year later and the rotors aren't evenly worn. It looks like was never much pressure put on the rear rotors to grind them to a clean finish like I see on the front. Part of this is because the regen braking, and I try to use this as much as possible, but is there anything else I can check on the caliper to make sure it's functioning properly?

 

I think there is a bearing issue, but I'm not sure which wheel it is. I jacked up the car and grabbed each wheel at 3 and 9 o'clock and at 6 and 12 o'clock, but couldn't see any differences between all the wheels. I can almost hear a difference when I turn to the left, leading me to the think the problem is the front passenger side wheel, but is there any way I can be more sure before I start replacing unnecessary parts?

 

Kinda like this?

 

I did that and noticed that the driver side front wheel was noisier. This may be a dumb question, but that means the driver-side wheel bearing is the bad one, right?

 

Just in case, do you guys know of any warranty on these wheel bearings Mileage is about 100K. Also, is MOOG a good brand? I see they are 170 at Autozone. Also, are left and right the same part?

 

How about 1A Auto, they have decent prices. I also found a set on eBay. The PAIR was $55 with a 10-year warranty!

 

Follow up: I wanted to check again and had someone press the gas (still in EV mode). I put a log under one wheel and had them speed up to 10 mph. I thought they almost sounded the same this time, but both seemed to have the whirring noise. Its hard to tell with the slower speeds. I also checked the rear and all I could do there was spin them by hand, but nothing stood out. There was no play in any of the 4 wheels. Is it more common that front bearings wear more quickly than rear? I think I'm going to replace both front bearings/hubs and rotors and pads in the rear. I'll go from there. Let me know any thoughts.

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