4. Wheels, Axles and Lubrication
The only wheels that are permissible are the Pinewood Derby wheels that are licensed by the BSA. Wheels may be from a kit, or purchased separately. The colored wheels sold by the BSA are allowed. All cars are required to have four wheels (two on each side), to insure proper tracking on the guide strip. Additional wheels for aesthetics may be added, if desired. You are permitted to sand or shave the outside tread of the wheel to remove imperfections and improve roundness. The inner and outer hubs of the wheels may be coned or polished. The outer hub double-step may be removed, if desired. No wheel modifications are permitted to reduce the diameter of the wheel to less than 1.17 inches (can be verified with calipers if required). The wheel tread must remain flat, and parallel to the wheel bore. No grooving or cutting of the wheel tread (e.g. H-cuts or V-cuts) are permitted. You may sand or polish the inside edge of the wheel, but you may not reduce the tread width to less than 7.5mm. You may not remove material from the inner tread of the wheel, nor from the inside face of the wheel. All lettering (both inside and out), spoke patterns, and tread bumps (bead markings) on the wheel must be present and intact. Both inside and outside faces of all wheels must be visible to inspectors when the wheel is mounted on the car.