It is actually really simple if you understand how the spacer works or have seen one. Toyota trucks have 12mm studs, the wheel spacers have 14mm studs. The wheel spacers since they have 14mm studs came with 14mm nuts that will not bolt onto the 12mm stud on the truck. Thus, a set of open ended 12mm lug nuts are needed to bolt the spacer to the truck.
They are manufactured by MC motorsports which machines extremely expensive custom forged wheels.
