You can get a kit that installs a metal plate on the bottom of the door. This metal plate has two channels in it that allow you to put a new rubber seal on.
https://www.amazon.com/M-D-Building-Products-87668-Universal/dp/B0006VAM1K/
You can cut the metal plate to length and the rubber seal length. I like to use a threshold on the floor for the garage door seal to interface with. When my door shuts I have a rubber on rubber seal.
https://www.amazon.com/dp/B00008YGQS/
Photo of my threshold that has been installed for over two years. I used two tubes of liquid nails construction adhesive and it has not moved so much as a centimeter even though I drive cars over it on a daily basis.
Photo of my garage door seal interfacing with my threshold.
Before I replaced my garage door seal and added a threshold I had issues with rainwater coming inside the garage during heavy rainstorms. With a seal and threshold in place I have had hurricanes come through here and I don't get a drop of water in my garage.