How tab width must be determined

[piotrunio-2004]

1. Sum the rendered widths of the following 52 characters: 
ABCDEFGHIJKLMNOPQRSTUVWXYZabcd  2. Divide by 52 with round to nearest. The way 
to do it is to add 26 and divide by 52.  3. Multiply by 8.   It's not eight 
spaces like some rumors say, but eight times the average letter width.