BSA pinewood derby wheels are well designed, but unfortunately the wheels vary considerably from mold to mold. Most of the wheels are not perfectly round and the tread surface is not even. Our BSA Speed Wheels are official BSA wheels which are sorted by mold number, and then precision machined to tight tolerances with our in house CNC (computerized) lathe using proprietary fixtures and tooling. The precision of this machining cannot be duplicated on hobby lathes. A set of our BSA Speed Axles are also included in this purchase. To provide you with an awesome set of wheels, we perform the following operations: The wheels are sorted by mold number. The wheel tread is lathed with True Track to achieve a perfectly round wheel, a flat tread surface, the inner edge of the wheel is also trued with a slight radius on the edges to replicate the look of a stock BSA wheel.