The  new C.B. Design Insert Wheel has many of the same great features as  other  C.B. Design Wheels; however, it has been designed to accept wheel  inserts.  Machined wheels are generally available in a relatively small  number of designs - one reason is many wheel designs do not lend  themselves to accurate reproduction when machined (or the machining  required is prohibitively expensive).  Initially available in a 15x7mm  size which fits Ninco "Classic" tires (21x7mm or 21x9mm), look for more  sizes in the future.  C.B.  Design 15x7mm Insert Wheels will accept Slot.It inserts (15mm) or you can  create your own inserts by turning down old plastic wheels. 
For more information, please visit the Slot Car Corner or Slot Car Corner Canada website.