Thanks for the info,I now see what happens.the door sits behind the opening not in the actual opening itself.thats why the door and opening can be the exact same size.the weatherstrip attaches to the front edge of the door.

The weatherstripping would typically attach to the inside edge of the RO and make contact with the door face.

Garage door rough openings are typically set in exact 1.5" increments larger than the size of the (actual) door to allow a 2x wood frame. In most all cases this wood frame is needed to extend past the concrete foundation stem wall at the bottom of the door so the finish jamb material has something to attach to.

This 2x frame can then be sheathed in prefab metal covers made just for this; then you add the weatherstrip molding on top of that. Optionally you can also add wood/vinyl/PVC jambs and heads on top of this frame, sometimes brickmold depending on the 1.5" increment the rough opening size was set back from the 9' width.

You will also need a wood buck on the inside face of wall to attach your track mounts to. Some other things too, if you are unaware you might want to do an image search on google.

Thanks for the help y'all.this door is hung and finished.turned out perfect

Glad everything worked out.

Good luck!