Pay attention to how wheel width, offset and backspacing relate to each other. Offset and backspacing are measured using the outside measurement of a wheel, not the bead flange. An 8" alum wheel will generally be 9" outside, + or - a 1/16" or so. A zero offset 8" wheel would measure 4 1/2" backspacing.
When choosing wheels it necessary to sometimes do the math yourself to know exactly what the wheels measurements are.