Is there any special tools required to change them?

 

If its a front wheel bearing u will need a 30mm hub nut socket n if its a rear wheel bearing u will need a 41mm hub nut socket.also u will need a good hammer n chisel.I started 2 change my front wheels bearing n ended up needing a complete hub cause the wheel bearings have been spinning on the hub.So ive ended up buying a second hand complete hub.