There are many ways to create a tar archive that would allow to limit the file size and break up automatically into incremental archives. If you want to do it with tar you should follow this short instruction.
Recreate archive from chunks:
tar -cvp '2011_03_13/' | split -d -b 4000m - archive.tar.bz2.
cat archive.tar.bz2.0* |tar -xpvf -