Where are hub bearings located?

When you remove the front wheels on a vehicle, there is usually a cap on the center of the 'hub'- the part you removed the wheel from by loosening and removing the wheel nuts. If you remove that cap with a flat screwdriver or other small pry bar, you will see the hub bearings inside. They are usually roller bearings that have grease all over them. You should read a repair manual if you are going to remove them and/or replace them.