I can't believe they even fit without rubbing, let alone a 1/2" of backspacing. With an 8" wheel, 3.5-4" is considered ideal, up to 4.35 will work with narrow tires, above that you will likely have frame rub. Get longer studs and use a spacer that is the width of the additional stud length. Around 1/2" will get you into the "ideal" zone.