Ground Cable On Seat Belt Screws?

Today I was trying to install my ground cable to the seat belt screws right behind the back seats when you fold them down. Now I have a 5/16" terminal on my ground cable which is 1/0 gauge Streetwires and the seat belt screws don't fit. Any suggestions and how did everyone else get through this problem? Also, does anyone know the max length the ground cable should be?