The best way to sway parents, and I'm a parent and grandparent, is to talk calmly and rationally with them. You've got two ears and one mouth for a reason. Start by asking questions and the really listening to, not just hearing, their answers. Ask them what they consider to be unsafe. Ask about their other concerns. Here's the hard part, when they are done talking thank them and walk away. Don't try to make your case yet. Take a day or two to consider their points and to come up with well thought out answers. Be ready to make reasonable compromises. Let them know that you see their side. Above all, keep your temper and don't whine. If they still say no, at least you only have a year or less until you are 18.