I've seen several descriptions but this one is just plain easy to read.

http://www.heeters.com/tirechart.shtml

Yes, bike tires need balancing.  Some weights are rim-mounted while others may be attached to spokes.

SouthernMD wrote on 12/31/69 at 16:00:04:

I specifically left that for someone else because I really don't know enough about it to advise someone else.  What I've read says that cruisers generally use bias-ply tires while sport bikes would be more likely to have radials.  Apparently the way the bands/fibers/cords overlay each other in the skeletal framework of the tire is the primary difference.  Bias-ply fibers overlap each other and generate more heat than radials but are more structurally rigid and create a rounder profile.  Radials have fibers that cross each other at 90° angles resulting in less heat generation but less rigidity.  This allows more flexing in the sidewalls.  Because of this, radials have shorter sidewalls than bias-plys.  The general advice seems to be that the bike is probably designed to handle best with a certain type so you should use whichever type is stock for the bike.  Either way, you should never mix the two.