You shouldn't be having conversations with a girl about the subject of whether she's ready for a relationship. That's already friend-zone discussion. If you see her, you like her, and you think she's interesting, you don't try to have heart-to-heart discussions. You say, "Hey, [x], what are you doing Thursday? I'd like to take you to dinner." It's pretty damn direct, she knows exactly what you're doing and you're not putting yourself in a position where she is unclear what you think about her. The worst thing that happens is she says "no" and you don't waste any more time on her. Or, I suppose, if you're really into her, you don't take no for an answer and tell her you're going to change her mind, and then just call once a week (no more often) until she either says you should stop calling or agrees. Any more and you're starting to be a stalker. Any less and you don't really care.