42.5 divided by 6 is 7.08 so measure 7.08 from the end and mark it, then measure from there. then when you put the light tab on make sure the mark is in the center of the tab
I think your math is off. He needs to divide by 4 to create 4 equal sections for the 4 lights he is mounting. Then he can mark the center of each section to place each mounting tab. Dividing by 6 gives him 6 equal sections but Jesse says he has only 4 lights that are 6" in diameter. You know, though, Jesse, dividing by 6 like Dylan says means you could actually fit 6 lights across. With 4 lights, each light would be spaced 4.625 inches apart. With 6 lights each light would be spaced 1.083 inches apart. You could also move the outer lights a little further out towards the edge of the bar so that you could have more spacing in between the lights. Do you have pics of the rack you are mounting on?
If you move the outermost lights out so that their edges are even with the ends of the bar and then evenly spaced them out you would have a little more room in between the lights, 1.3 inches vice 1.083, and it might look a little cleaner.
