Code:
PS1='${debian_chroot:+($debian_chroot)}\t \u $(if [ ${#PWD} -gt 30 ] ; then myPWD="${PWD:0:12}…/\W" ; myPWD="${myPWD:0:25}…" ; else myPWD=$PWD; fi ; echo $myPWD) $ '
It will display full paths smaller than 30 characters entirely, but for longer paths it will get only the first characters of the whole path, and the fist characters of the last folder in the full path.
The end result is something like:
HH:MM:SS tuxguy /home/tuxguy/mystuf.../xmas...