My '97 is equiped with 15" Borbet wheels and 205/50 tires. The car darts side to side with changes in grade/road crown. The manual says alignment should be set to zero toe in/out. I've never heard of this, wouldn't some toe in or out provide more straight line stability?

 

Not really, toe in your wheels are pulling inward while moving forward, this will wear the inside of your tires. Toe out your wheels are pulling outward as they move forward wearing the outer part of your tire. In road racing these adjustments are dialed in to give more stability on the track, but for the street they do not really serve a purpose. If your car is lowered, get a camber kit and get your car aligned.

 

darting like you described is generally caused by a lack of caster.

 

Ah yes, castor. That makes more sense. I'll have the alignment checked and try adding more castor angle. Thanks.