Do not force the nuts on the studs! When I installed my side steps using the OEM studs (3 studs per mounting bracket) I had to use a thread die on every stud. The problem is the studs have a thick coat of paint on the threads and the thread die removes the paint in the threads. It was a PIA and took a lot of time working the die back and forth. I did not want to snap off or strip any of the OEM studs just by forcing the nuts on with a wrench. The nuts went right on after I removed the paint from the threads. Do not over torque the nuts.
The post was to help with the installation of the nuts on to the studs and my experience that could be helpful to someone that is having a problem. Not if I know that the studs are metric which they are.Hopefully you didn't try to put SAE nuts on metric stud.