Lug Nuts and Studs
The single greatest concern with lug nuts is that you have adequate engagement between the lug nuts and wheel studs. The picture on the left is what you shouldn' t have. Notice how the studs don't stick out past the lug nuts. These wheels studs are too short. The engagement between the nut and stud is marginal. The general rule is that the number of engaged threads should equal the diameter of the wheel stud. In other words if your wheel stud 12mm in diameter than the lug nut should engage at least 12mm of thread. The Southern California Timing Association, which governs the racing at Bonneville, requires at least 5/8 inch of thread engagement. The SCTA also prohibits the use of closed-end lug nuts. This Mustang is an example of closed lug nuts. We simply don't have a clue about what's going on with closed lug nuts. It's difficult to see how many threads are engaged. The worst case scenario is where the wheel stud bottoms out on the inside of the lug nut and...