The hole you are talking about is 5/16". I'm using 3/8" allthread and so will have to drill the hole a little larger. Not a big deal. 3/8" will work just fine in these. Of course that means you should be able to use 1/4" just fine also.
This component is really not meant for that type of application, but the Halex #3 hanger is tested to hold a pull force of 50lbs. Thank you