Do you have to choose to send them once they are completed? I think if you don't do that then it will save them locally for you but no one else can pull them up.
The Official Mario Kart Wii thread
I've never chosen to send them or anything, they just automatically are posted I think. Maybe it has something to do with your Mario Kart Channel options/settings?
I definitely have times for people, just most haven't actually raced most courses via time trial...