A little toe-in compensates for the tendency of the tires to toe out a little while rolling. Since it's impossible to get a rolling measurement, the 1/8" toed-in setting works about right. The tires are running as close as possible to straight ahead after the truck gets into motion.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!