Question

how can I set presets for radio buttons with jQuery?

Here is a simple example: http://jsfiddle.net/EpQgr/

<select>
   <option>option 1</option>
   <option>option 2</option>
</select>

<div>
    <input id="radio1_0_0" type="radio" name="radio1" value="1" />x
    <input id="radio1_0_1" type="radio" name="radio1" value="2" />y
    <input id="radio1_0_2" type="radio" name="radio1" value="3" />z
</div>
<div>
    <input id="radio2_0_0" type="radio" name="radio2" value="1" />x
    <input id="radio2_0_1" type="radio" name="radio2" value="2" />y
    <input id="radio2_0_2" type="radio" name="radio2" value="3" />z
</div>

The pre set options should be something like this:

//option 1
$("#radio1_0_1, #radio2_0_2").prop("checked",true);

//option 2
$("div input:first-child").prop("checked",true);

Answer 1

change your html code in this way:

<select>
   <option value="">Choose a preset</option>    
   <option value="#radio1_0_1, #radio2_0_2">option 1</option>
   <option value="#radio1_0_0, #radio2_0_0">option 2</option>
</select>

and the JS

$('select').on('change', function() {
    var v = $(this).val();
    if ($(v).length) {
        $(v).prop("checked", true);
    }
});

The elements to check are stored inside value attribute of each option.
This solution avoids having to enter each preset inside the handler of the select. If you need to insert a new preset just add the option with a new selector

see jsfiddle: http://jsfiddle.net/8f7Nw/2/