To get full width use owl-carousel outside your div wrappers.-
$(document).ready(function() {
$("#owl-demo").owlCarousel({
navigation : true
});
});
<div id="owl-demo" class="owl-carousel owl-theme">
<div class="item"><h1>1</h1></div>
<div class="item"><h1>2</h1></div>
<div class="item"><h1>3</h1></div>
<div class="item"><h1>4</h1></div>
<div class="item"><h1>5</h1></div>
<div class="item"><h1>6</h1></div>
<div class="item"><h1>7</h1></div>
<div class="item"><h1>8</h1></div>
<div class="item"><h1>9</h1></div>
<div class="item"><h1>10</h1></div>
<div class="item"><h1>11</h1></div>
<div class="item"><h1>12</h1></div>
</div>
#owl-demo .item{
background: #42bdc2;
padding: 30px 0px;
margin: 10px;
color: #FFF;
-webkit-border-radius: 3px;
-moz-border-radius: 3px;
border-radius: 3px;
text-align: center;
}