Sublime Text 3, convert spaces to tabs

I know there are a lot of posts about this, but I couldn´t get it to work.
I use tabs for coding. Is there a way, to convert always spaces to tabs? I.e. on open and on Save files? Anyone got an idea?

// edit:
My desire is to do this automatically! -> open, save or on the fly
Does anyone know how to do?

I tried this:

import sublime, sublime_plugin, os

class ExpandTabsOnSave(sublime_plugin.EventListener):
  # Run ST's 'expand_tabs' command when saving a file
  def on_pre_save(self, view):
    if view.settings().get('expand_tabs_on_save') == 1:
      view.window().run_command('expand_tabs')

And here are my user Settings:

{
    "auto_complete_selector": "source - comment, meta.tag - punctuation.definition.tag.begin",
    "auto_indent": true,
    "detect_indentation": true,
    "draw_white_space": "all",
    "ensure_newline_at_eof_on_save": true,
    "expand_tabs_on_save": true,
    "font_face": "SourceCodePro-Regular",
    "font_size": 10,
    "format_on_save": true,
    "ignored_packages":
    [
        "Vintage"
    ],
    "indent_to_bracket": true,
    "open_files_in_new_window": false,
    "smart_indent": true,
    "tab_size": 4,
    "translate_tabs_to_spaces": false,
    "trim_automatic_white_space": true,
    "trim_trailing_white_space_on_save": true,
    "use_tab_stops": false,
    "word_wrap": false
}