Alignment Question....help

OK - when I use alignment strings and the specification says 1/16" toe-in, does that mean the difference between the forward and rear measurement, from the edge of the rim to the string, should be 2 x 1/16" = 1/8", or the difference between the two should be 1/16", or do I need to factor in the diameter of the tire

Searched the forum but cannot find any advice.......help

Alignment Question....help