These Red Dirt Derby precision machined and polished axles are grooved in order to reduce speed robbing friction caused when the wheel is in contact with the axle. Additionally, these are also bent 2.5 degrees to enable steering of your car (rail riding). Lastly, these axles were engineered with an increased diameter in order to reduce wheel wobble. These are not original BSA nails, these are precision machined axles. Check your rule book.