Use the `disabled` attribute to disable an input radio. Clicks will be suppressed until the disabled state is removed.

```html
  <sd-radio-group name="radio-group" label="Disabled group" required>
    <sd-radio value="1" disabled>Radio 1</sd-radio>
    <sd-radio value="2" disabled>Radio 2</sd-radio>
    <sd-radio value="3" disabled>Radio 3</sd-radio>
  </sd-radio-group>
</form>
```