When you install alloy wheels on your MG you will likely need to procure different log nuts, longer wheel studs, or both. There are two basic style of interest here, Cone Seat or Mag Seat (commonly called straight shank). You will need the style that matches the holes in your wheels.


One significant issue with alloy wheels is that they will most often have thicker center section than the original steel wheels. Alloy wheels sometimes use a cylindrical drill through hole with a flat face counterbore. This requires the straight shank lug nut with a heavy flat washer. The primary advantage here is to allow the new wheels to work with the original studs. The straight shank lug nut reaches through most of the thickness of the alloy wheel center to screw onto the original length stud.

When the thicker alloy wheels use cone seat lug nuts, the wheel studs will most likely need to be changed to longer studs. If you use a standard type steel wheel for the spare tire, or if you switch regularly between steel wheels for street use and alloy wheels for competition, you might need to keep two different sets of lug nuts to suite the different wheel types. If you run wheels with exposed lug nuts (no hub caps) you may prefer to use chrome cap nuts for appearance and corrosion resistance. Using cap nuts with thin wheels and long studs requires long cap nuts. While the long cap nuts may fit inside of standard wheel covers (hub caps), they may not fit inside of center covers for the alloy wheels. I run my alloy wheels with no center covers so I can use the longer cap nuts and not need to carry the second set of lug nuts for the thinner wheels.

Measure the hole diameter and thickness of wheel before you go shopping for new lug nuts. Also note the required thread size. MGA originally has 7/16-20-UNF studs. MGB originally has 1/2-20-UNF studs. MG Midget originally has 3/8-24 UNF studs.

When shopping for longer studs, one critical dimension is the diameter of the spline that will be pressed into the axle bearing hub. See WL-103 for Replacing Wheel Studs.