To replace the rubber seal on the bottom of a garage door, remove the existing seal, obtain a replacement seal of the required size, and position it in the groove at the door's bottom with its lip facing inside or outside depending on the slant of the driveway. Finally, trim the excess seal.
To remove the existing seal on the bottom of a garage door, open the door, and slide the seal out from one side. To obtain a replacement seal, first measure the door's length across its bottom, and buy a seal of the same measurement.
If the driveway slants in a downward direction towards the door of the garage, position the new seal with its lip facing inside. Otherwise, position the seal's lip outside the door.
To attach the seal in the groove at the door's bottom, place one of its ends into the door's groove, and feed it in the groove until you reach its other end. If the seal comes with a groove of its own, position the groove so that it matches with one of the door's ends. Move the seal gradually till you reach the other end. Have someone to assist you while doing this. Do not stretch the seal when attaching it to the door's bottom.
After installing the new seal, trim the excess portion with a utility knife. Cut as close to the door's end as possible.