Assuming this is a 4x4 you are working on, the rotor/hub/bearing all comes off as a unit. You can then remove all the wheel studs and the rotor falls off. Did you remove the four bolts in the back of the steering knuckle so you can pull the hub out? If it's never been apart there is a good chance the bearing is rusted in there pretty bad. If you don't have a huge hub puller, something some guys do is to loosen all the bolts and then use a socket extension or some other thing between a bolt and something on the axle then start the truck up and use the power steering to "jack" the hub off. Do a little at a time between oposite sides. I have never done this, just read about it. Mine came right off when I replaced my axle seals becasue they had been apart before and anti-seize was used. I removed some on a '97 with a big hub puller and that was even tough. Also to keep from damaging your axle seals it would be a good idea to tie wire your axles to the housing so they don't pull out as you pull the hubs off.
I see this is your first post, welcome to TDR land.