Deactivate selections in a set of radial groups using a button and JavaScript

Here is what I am looking to do.  I have a form that I built that must use Radial buttons for other functions but users can select an accedent a radial button and not have the ability to deselect it. I have things grouped into lets call them radial button famlies or groups.  For instance I have radial groups named Trucks1, Trucks 2, Trucks3 and another group or family named Cars1, & Cars2. Inside each group there would be a individual radial button for big, little, and small. 

I want a button that can deselect for all of Trucks and another button that can deselect for all of Cars.  It would be very helpful since I am new to this if you use trucks and Cars in your example to help me understand what I am doing correctly (or in this instance what I am doing incorreclty). 

Thanks!