When you have the carpenter’s square barely touching the face of the string, make a 1” mark parallel with the string. You will do this at the front cross mark that was first made in front of the tire and then at the 2’ tape mark also. Then move to the opposite tire and do the same.

Once both tires have their two 1” marks (parallel to the string) you’ll need a pen and paper to log two measurements. With a tape, measure the distance between the two ‘parallel to string’ marks that were made immediately in front of the tires. Then do the same measurement at the 2’ forward marks. The following pic shows what I came up with upon returning from the last Branson NATs only to find a badly worn L. front tire.

I used an arrow to point at the word tire so that I wouldn’t get the numbers reversed so, as you can see, the distance between the two strings, immediately in front of the tires, was 63 ½”. At the 2’ foot forward mark the measurement was
64 ¼” therefore, I was running with a ¾” toe out, NOT a wise thing to do.

At this point, if you need to do some adjusting, you’ll need to break the jam nuts loose on your tie rod and get busy. And remember, you’ll need to reset the strings and do all the previous measurements and marks again to find out what the new measurements are giving you in toe in or toe out.