Radio onClick - replace img src with title not firing until 2nd click
===

Here's a script which replaces the img src with the title tag of whatever radio is clicked.

    var imgFldr = '/uploads/2012/07/';
	$("input[type='radio']").click(function() {
	$('#'+this.name).attr('src', imgFldr+this.title);
	});

    <input type="radio" name="lift" id="standard_left" value="Standard left" title="Cellular-Lift-Type-Standard-Left.jpg" onclick="doCalc();">Standard left<br>
    <input type="radio" name="lift" id="standard_right" value="Standard right" title="Cellular-Lift-Type-Standard-Right.jpg" onclick="doCalc();">Standard right<br>
    etc. etc.

Everything works perfectly once you click a radio and then click another.  The page starts off with NO radios selected, then you select one and it doesn't change the image.  The second click it does change it.  

Is there something I need to change letting the script know there will be no selection starting out?