Most I've carried is around 10 pounds.

Now, my work is only a mile or two away, so I'm not carrying the full stock of repair equipment some of the dudes and dudettes here are. But even if I was, a nice set of supplies probably wouldn't be more than 5 pounds altogether. You'll be totally fine with a 55 pound limit for just about everything short of car-replacement grocery shopping and moving to a new place, I'd say.