Ajax Jquery Json success problems

Hi I would love to get some help with a problem I have that I just can't solve because of my lack of knowledge I have first of all some html coding with a few radio buttons with a attached span to each:

<div id="output2">
<input type="radio" name="tid" value="1"><span class="green">Span 1</span>
<input type="radio" name="tid" value="2"><span class="green">Span 2</span>
 <input type="radio" name="tid" value="3"><span class="green">Span 3</span>
 <input type="radio" name="tid" value="4"><span class="green">Span 4</span>
 <input type="radio" name="tid" value="5"><span class="green">Span 5</span>
</div>

I have an ajax request sending off a request to a php script the success part is empty here because this is where I have my problem I have no idea what to do here

$.ajax({
           type: "POST",
                                url: "fetch_time.php",
                                data: "datum_id=" + datum_id,                   
                                beforeSend: function() {
                                    $('#output2').html('<img src="#" alt="" width="24" height="24">');
                                },
                                success: function(json) {   
            });

I get a return value from the php script in the form of a json file that looks for example like this:

[{"tid_id":"4"},{"tid_id":"5"}] 

What I want to do is to use these values from the json file the 4 and 5 and compare them to the value of the radio buttons, and IF the value from the json file is the same as the value on that specific radiobutton I want the radiobutton to be disabled and the class of the corresponding span to change from class="green" to class="red" OR just change visibility on the radiobutton and the span to none.

If anyone could help me out I would be very greatful

Sonny Österlund