Radio Buttons
Watir sets or clears radio list items by looking at the attributes available in the <input type="radio"> HTML tag. Common attributes are id and name. For complete list see HTML Elements Supported by Watir.
What you see in the web browser:
Click Me: 
This is the tag in the HTML source:
<input type="radio" name="clickme" id="one">
id Attribute
Watir code to set a radio list item using the and id attribute:
ie.radio(:id, "one").set
Watir code to clear a radio list item using the id attribute:
ie.radio(:id, "one").clear
name Attribute
Watir code to set a radio list item using the name attribute:
ie.radio(:name, "clickme").set
Watir code to clear a radio list item using the name attribute:
ie.radio(:name, "clickme").clear
