use script
https://github.com/moby/moby/blob/master/contrib/download-frozen-image-v2.sh
usage:
chmod +x download-frozen-image-v2.sh
./download-frozen-image-v2.sh "<folder-name-where-image-will-be-saved>" <docker-image-name:docker-image-tag>
tar -cC "<folder-name-where-image-will-be-saved>" . | docker load