When it comes to mounting your wheels, there are different styles of lug nuts and lug-nut mounting surfaces. Most lug nuts are a tapered design like the four on the left. These are used to both align and center the wheel. The two lug nuts on the right are a flanged style that use the narrow center shank of the nut to key into the wheel and help center it while the washer is tightened to the wheel face. The lug nut in the center is the best of both worlds as it has both a flange and a taper, but it is commonly found only on the 1/2-ton and lighter trucks.