It's a really nice tool and it is very helpful to try to reset your camber. I just used the tire on the same side that was aligned properly but you have to adjust it for the left and right sides separately.
Used it on my old 61' after rebuilding the front end. Takes a little practice to use it.
Nice tool! Helped me get my rear camber straightened out.
It allowed me to adjust my camber from -3° to 1° on a 07 yukon. Alignment shops keep trying to up sale me on parts that where just replaced. This is a must have!