trailer bearings / tires

[Sean]

Alright I have never replaced/repact the bearings in a triler, I dont even know exactly were they are located ::), I know in the hub but have never seen them.
The boat/trailer is up on stands and the lugs on the tires are off/loosen (WOW was that hard, rusted and stuck!) I did a search on the site but couldnt find to much on the , "how To" of the bearings process, so any help, pointers, directions will be apreciated!!
Also, can you test tire pressure with the tire off the trailer?? ???