Change default tab width to 4

README.markdown

@@ -28,7 +28,7 @@ then simply copy and paste:
   the first file in a brand new Ruby project might very well be derived from
   your `.irbrc`.  I consider this a feature.
 * If your file is consistently indented with hard tabs, `'shiftwidth'` will be
-  set to your `'tabstop'`.  Otherwise, a `'tabstop'` of 8 is enforced.
+  set to your `'tabstop'`.  Otherwise, a `'tabstop'` of 4 is enforced.
 * The algorithm is rolled from scratch, fairly simplistic, and only lightly
   battle tested.  It's probably not (yet) as good as [DetectIndent][].
   Let me know what it fails on for you.

plugin/sleuth.vim

@@ -15,7 +15,7 @@ function! s:guess(lines) abort
   let podcomment = 0
   let triplequote = 0
   let backtick = 0
-  let softtab = repeat(' ', 8)
+  let softtab = repeat(' ', 4)
 
   for line in a:lines
     if !len(line) || line =~# '^\s*$'
@@ -79,7 +79,7 @@ function! s:guess(lines) abort
   elseif heuristics.soft != heuristics.hard
     let options.expandtab = heuristics.soft > heuristics.hard
     if heuristics.hard
-      let options.tabstop = 8
+      let options.tabstop = 4
     endif
   endif