She is apparently trying to prevent you from doing something that she knows could potentially be dangerous to you.

We are only hearing one side of the story.  You may be immature and irresponsible for your age.  There may be other factors that we don't know about when she made the decision.  

I would suggest that you cool it until you are on your own.

Like someone said, out of respect you should obey and listen to your parents. We may not appreciate them now or give a flying flop what they say or think, but we will later.