Yeah, I know what it is, I am just not agreeing with using it in setting your toe. If that was a viable method, then there would need to be a spec for how far away from the wall you could be. Trust me, use the tape measure, and set it to 1/4" toed in.

You must measure from the same point on the tire at the back and the front for the measurement to be meaningful. You can determine that a number of ways. In the olden days we used to have a tire scoring tool that made a mark all the way around the center of the tire, but I have been trying for years to find one on eBay with no luck. Now I use the tool I got from Harbor Freight which measures from the outside edge of the tire, but I used to just look very closely at the tread design and mark the center of the tire with a pen.

Dude, I have been doing it this way for over 30 years and I have never had tire wear problems. I set EVERYTHING to 1/4" in because I found, over the years, that was more or less the factory toe setting for every car I aligned in a shop.