How may miles do you have? Even if they are sealed bearings (and I don't know if they are), they should last at least 100K. If they aren't sealed, then you should be able to repack them. At any rate, when you do it, take a look at your brake pads to make sure they are OK.
Yeah, why. They are sealed and like was said, should last 100K miles (or more). To remove one you need to remove the wheel, remove the caliper, remove the rotor, remove the large nut in the center of the axle, remove a few bolts (3 or 4 via a hole in the wheel stud mounting surface), remove the bearing. Reverse to install.
your going to need a press to get it apart and to press everything in. also when you remove the axle nut, MAKE SURE you get the one side that is notched down on the axle up all the way or your going to F@#k you axle up.i know i thought i had a couple of those chesialed (SP?) up and screwed the axle up.
03 toyota matrix XRS 6 speed, lunar mist,factory 17 inch rims w/firehawks- summer tiresfactory 16 inch rims with dunlops- winter tirestrd sway bars, trd strut brace, trd sport muffler,trd quick shifter,trd cold air intake, toyota tundra dual horns,factory toyota wing from toyota canada, both front door handle modsNEW pioneer AVIC-D1 nav unit, XM radio installed