toe-in vs toe-out experiment
 

I've always been curious how front toe affects straight line stability of a car.

So, I adjusted my front toe to a purposely ludicrous 0.75 deg toe-out per wheel and drove to work and back a few times (200 miles total), a mix of Michigan freeway speeds (75 - 80, occasional bursts to 95), city, and country 2 lanes. Also made sure to try a few fun 2nd gear corners.

It did seem to require slightly more corrections to stay traveling in a straight line. I noticed nothing at lower speeds or in fun corners. And to be honest, if I didn't know I changed the alignment I probably would not have thought anything is amiss (until the front tires got bald before the rears, anyhow ...).

Not making any suggestions on aligning a car, just sharing a silly experiment I made.

From what I noticed, front toe doesn't effect straight line stability. Even if the front corners are different, the car will self center and the steering wheel will be off. So essentially the front corners are always the same and the car will track straight.

However, front toe definitely effects turn in. My street car is set about 1/8" in. Decent turn in under minimal loads. My DE car is set at about 1/8" out. Nice turn in under heavy loads. Different animals.

I wanted a bit of toe out for quicker turn in autocrossing. The shop that did the alignment recommened zero toe or the car would be a bit darty on the street.

I just went from 3/16" toe in to 1/32" toe in, and the steering is more responsive. Previously, I had a little dead spot on center, which is now gone. The car is not darty.
-Scott

Yes, but you went from toe in and still have toe in. I'm curious if a small amount of toe out will make the car darty. I've had some toe out on other cars and it wasn't a problem.

how about rear toe, what are the effects there?

On the rear you definitely want toe in. Toe out makes the car want to spin.