Overview
To use custom radios, simply create a wrapper div with the class .custom-control.custom-radio and create <input> and <label> elements inside it.
Give the <input> a class of .custom-control-input and the <label> a class of .custom-control-label.
Radios
<div class="form-group">
<div class="custom-control custom-radio">
<input type="radio" checked="" class="custom-control-input" id="exampleRadio" name="exampleRadio" value="customEx">
<label class="custom-control-label" for="exampleRadio">Radio 1</label>
</div>
<div class="custom-control custom-radio">
<input type="radio" class="custom-control-input" id="exampleRadio2" name="exampleRadio">
<label class="custom-control-label" for="exampleRadio2">Radio 2</label>
</div>
</div>
<div class="form-group ml-3">
<div class="custom-control custom-radio">
<input type="radio" disabled="" checked="" class="custom-control-input" id="exampleRadio3" name="exampleRadio2">
<label class="custom-control-label" for="exampleRadio3">Disabled</label>
</div>
<div class="custom-control custom-radio">
<input type="radio" disabled="" class="custom-control-input" id="exampleRadio4" name="exampleRadio2">
<label class="custom-control-label" for="exampleRadio4">Disabled</label>
</div>
</div>