The wheel bolt holes are flush on Hub Pilot and beveled stud holes on the Stud-Pilot.
While almost all aluminum alloy wheels look very similar, except for their different design vent holes, there is more of a difference in them that can be normally seen by naked eye, when they are already mounted on a vehicle. Here are the basic two types of commercial wheels determined by how the wheel is centered on the hub. The Stud piloted wheels have tapered stud holes and the lug nuts have a matching taper. The centering of each lug nut in the stud hole of the wheel will cause the wheel to be centered on the hub. The hub hole in the wheel only serves to allow hub clearance. While the Hub piloted wheels use the center hole of the wheel (hub bore) to fit over the matching size ridge on the hub. The wheel is centered on the hub by the hub bore. The lug nuts will have a flush face in contact with the wheel. The lug nuts only secure the wheel to the hub.
In hardware, Stud-piloted dual wheels require both inner and outer nuts – total of 20 per dual assembly. With tandem axles on both tractor and trailer, which means: 8 duals x 20 nuts ea. = 160 nuts. While in hub-piloted wheels there are no inner nuts in hub-piloted wheel systems. If you consider duals only, you cut your fastener inventory in half. To position the wheels on axle ends, the The Stud piloted wheels use the studs and ball-seat cap nuts. You need both right-hand and left-hand threads, for the right and left sides of the vehicle. So, you need more nuts, do more labor installing and removing them, and need four different types of nuts in inventory. While the Hub piloted wheels metal projections, called the “tangs” provide the proper alignment. There are no inner nuts in hub-piloted wheel systems. Ball-seat nuts, for stud-piloted systems, and the new, two-piece flange nuts for hub-piloted systems, work totally differently. In some cases, the hardware won’t interchange, because sizes and threads are different. But even if you could get nuts to fit, interchanging them it is not suggested and could cause damage to the wheel or worse.