JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/css/bootstrap.min.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/js/bootstrap.min.js"></script>
<div class="container">
  <div class="row">
    <div class="col-sm-12">
      <form class="form-inline text-center">
        <div class="form-group">
          <select class="form-control w140">
            <option>foo</option>
          </select>
        </div>
        <div class="form-group">
          <select class="form-control w140">
            <option>foo</option>
          </select>
        </div>
        <div class="form-group">
          <select class="form-control w140">
            <option>foo</option>
          </select>
        </div>
        <div class="form-group">
          <select class="form-control w140">
            <option>foo</option>
          </select>
        </div>
      </form>
    </div>
  </div>
</div>

CSS

.form-inline .form-control.w140{
   width:120px; 
}