Show tar files sizes
Solution 1:
This should list all files and detailed information about them:
tar -ztvf somefile.tar.gz
Solution 2:
Use
tar --list --verbose --gunzip --file backup.tar.gz > backup_list.txt
to create a file containing a list of all the files in your archive.
You can then grep foo backup_list.txt to find things, or edit, sed, cut, view, etc.