Is it better to use radiant barrier or insulation on a garage door in hot weather ?

You can use radiant barrier or insulation on your garage door in hot weather. It need when the garage door be hot for hot weather.  Radiant Barrier Foil will only be effective if the sun catches direct sun. Another way to cool the garage is to help ventilate it. If you have a pulldown staircase or scuddle hole, prop it open and then set the proximity switch on the garage door opener to get it to stop an inch or two before completely closing. Air will come under the door, through the garage, up and out the attic door and then through the attic.