They actually make a grease packer that you put the bearing in and step on it and it packs grease all threw the bearing.Its fairly cheap being about 20 bucks so I would get one cause you really need to pack the bearing good with grease cause that is what keeps it lubricated and it will fail if you do not have enough in there.Doing it with your hands is possible but you need alot of grease on it to make it last.DO NOT USE WD 40 it will not work.It has to be a high temp wheel bearing grease to be right.The most important part of the job is to make sure you have plenty of grease and to have the wheel bearing tightened enough because the tire could become loose and possibly fall off if it not right.Make sure you get the two new seals also while your doing it because those keep the dirt out and the grease in

 

NOT WD40!!! you need WHEEL BEARING GREASE! it must be wheel bearing grease... WD40 is a leightweight oil.

Remember never to Buy cheap bearings... Go buy timken... expensive? YES. Reliable... hell yeah. Dont let them talk you into SKF... they suck.

Also, Never mix grease... thouroughly clean the bearings before you install them, then repack them with your own grease. Mixing grease is usually frowned apon. Make sure its wheel bearing grease.

Jim