Near the center of the wheel are mounting holes that are tapered to fit tapered mounting nuts (lug nuts)
that center the wheel over the hub.
The rim has a hole for the tire's valve stem and a drop center area designed to allow for easy tire removal and installation.
Wheel offset is the vertical distance between the centerline of the rim and the mounting face of the wheel.
The offset is considered positive if the centerline of the rim is inboard of the mounting face and negative if outboard of the mounting face.
The amount and type of offset is critical because changing the wheel offset changes the front suspension
loading as well as the scrub radius.
The wheel is bolted to a hub, either by lug bolts that pass through the wheel and thread into the hub, or by
studs that protrude from the hub.
In the case of studs special lug nuts are required.
A few vehicles have left hand threads (which tum counterclockwise to tighten) on the driver's side and right-hand threads (which turn clockwise to tighten) on the passenger's side.
All other vehicles use right-hand threads on both sides.