If you don't hear any noise while driving (humming or droning from the front, proportional to speed), then it is unlikely there is enough wear on the bearings to require replacement. Check adjustment first, but I also suspect you'd find problems other than the bearings more likely to cause your braking vibration.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7