I am a motorcyclist, but your mother makes a good point. She is correct in saying someone in a car will screw up. We are basically invisible to car drivers. I have had MANY near misses because a car does something stupid. I ride VERY defensively, but sometimes that just doesn't cut it. One night last week a car made an illegal left turn and just about ran over me. There was nothing I could do. It happened so fast. The car was coming toward me in the other lane behind a car, then out of the blue the back car just crosses the center line to turn left and I was RIGHT THERE! I locked up the bike and pulled to the right and luckily the car saw me at the last second and slammed on their brakes too. We missed by mere inches. Then the real battle was on for me to regain control of the bike, keep it upright and not hit the curb. I was going no more than 30 or 35 miles per hour and my bike is fairly lightweight. The fact that I ride a light bike is probably what saved my life. It is an 1100 cc but is built light. If it had been a big heavy cruiser I don't think I would be alive today. Anyway this was just the latest event where a car nearly killed me. It happens everyday to some unlucky motorcycle rider. It doesn't matter how skilled you are, or how careful you are. If a car does something completely stupid and unexpected there is nothing you can do. I know this is not the answer you want, but try to give your poor mother a break. Enjoy the off road biking for a few more years and when you are old enough to do it on your own get the road bike. If you get killed then at least your mother will be able to know that she had nothing to do with the decision. She must be fairly cool to let you ride a dirt bike all of these years. Imagine how she would feel if she lets you get the road bike and then you get killed. How could she go on? You really shouldn't put her in that position. In 2 and a 1/2 years you will be 18 and can then do whatever you want to without her permission. I know it seems like an eternity when you are 15 and a 1/2, but you'll be 18 before you know it. Sorry kid, I've got to go with your mother on this one. Stop pushing. Prove you are the man you claim to be by accepting your mother's decision for now and knowing she loves you.