Rear Tire Alignment

Hi all, new here and like what I see! I have a question about the best way to align the rear tire on my '03 Softail. The manual says to measure from the middle of the axle bolt to the middle of the pivot bolt and match both sides within like a zillionth of an inch. Well, its pretty tough to find the exact middle of the head of a bolt! Is there a tool or a better way to do this and does it really have to be that exact?

aligning rear wheel

get an old metal coat hangar. bend 90 Degrees at one end and place on center of swing arm pivot bolt. bend the other end 90 degrees so it centers on the axle. Go to the other side and reposition. if both ends are centered on the bolts you areall set. otherwise, adjust accordingly until they arecentered. Misaligned tires will wear more quickly and cause more vibration. Its worth the effort.

Thanks for the tip, I'll try that. I had been using a tape measure, but its hard to get the thing in there straight. I thought I seen in my shop manual that there is an alignment cap you can put on the "head" side of the pivot bolt to make it's center easier to find, I'll have to page thru there and look. Thanks again.