Too much rear toe?

[yz490]

As track season is fast approaching for me and my 2008 e90 m3, (my dual purpose daily driver/track car), I recently upgraded to a 275/35/18 square setup, and just had the car aligned today. I had them pull the pins, and asked them (At Speed Motorsports, Baltimore MD) to give the car as much negative camber as possible and set it up with neutral toe.

The car is now at -1.5 up front on both sides with 0.00 degrees toe, and -1.6 both rear, but with A TOTAL REAR TOE of 0.40 degrees, 0.20 per side. Obviously there was a misunderstanding that I failed to notice before I got home and looked at my printout.

Looking at about a million posts in the last hour, it seems that I might have been a bit hasty in thinking that neutral rear toe was the way to go: perhaps a tiny bit of toe-in might keep me from killing myself this season, and my shop may have simply assumed as much. But is 0.40 degrees total rear way too much? Will this hamper turn-in or the ability to rotate the car? Will the rear tires be destroyed in a matter of days? Is 0.40 anywhere even close to spec? For lack of a better phrase, WTF??

Thoughts?

[HP Autowerks]

A little rear toe-in can help generate slip angle and thus cornering force. However, too much rear toe-in can cause some instability in corner entry and may cause the rear to slide.

[yz490]

So is 0.20 degrees to in both sides too much for this car?

[HP Autowerks]

Originally Posted by yz490

So is 0.20 degrees to in both sides too much for this car?

On E9x M3, 0.20 each side is too much, you should be at no more than 0.20 total toe-in.