Camber is the tilt of the tire in or out at the top, and that is what causes off-center wear. If you've got wear at the inside of the tread, that's negative camber,and it probably means there's wear at the king pins, or the wheel bearings are a little loose. Once you're sure all the wear points are corrected, then it might be necessary to bend the axle to correct the camber angle. That's a professional-type operation with special tools and HEAVY DUTY jacks!
Caster is corrected by using a tapered shim between the axle and the springs, or if one side is wrong, the axle can be twisted by using special lever arms and hydraulics. I grew up around a shop where we did straight axle alignments, and it's a tough job sometimes!
Jerry
