This is not true. You need to understand more about this before posting. There is no toe in/out on the rear. That is just insane. There are no tie rods etc unless you have some one of a kind special edition vehicle.
The only thing is the camber and yes, if you use spacers or different offset wheels on the rear you are making more contact with the inner part of the wheel thus you will be riding on that mostly and nothing else. So expect your treadwear rating to be cut in half. If you want to extend the life of the tire, since most are directional, every 10K mi or so you take the wheels so they can unmount the tire and flip it around on the same wheel. When installing then you then switch wheels. mark the outer part of the tire with a tire pen so you or installer doesn't get confused. So let's assume you have treadwear of 400 which is about 40K mi or so. Because of the natural negative camber and the offsets/spacers etc. you are only going to get about 20K out of that tire. So at 10K you flip it around and then at 20K you can do it again. And again at 30K if the tire still has a bit of life and at 40K they're done.
If your car is already aligned there is no need to do another alignment unless you want to waste your time and money. Just because you are getting wider wheels or changing the offset is not going to do anything to your aligment. If anything just reset your Active Steering. This is a must do.
If you don't want to believe me, it's your choice and your money. I really don't care about either.

 

Camber does impact the contact patch amount... The more negative camber,, the less tire contact,,,, and more vehicle wieght on a lesser contact patch.. Which makes all the cars wieght ride on the inside 2 inches of the tires corner edge.. Negative camber is what totally kills the tread on the inside corners ......

 

The rears do have toe-in and toe out. It is not achieved through tie rods but by adjusting the eccentric bolts in the rear suspension arms. You can look it up in realoem.com under REAR AXLE, then REAR AXLE WITH SUSPENSION.

 

Hmm..... Ive never heard,,, or seen toe in /out being done on the rear.. The essentric bolts dont have any adjustment ability... Can u elaborate.... I am interested in ,,,,,, how can toe in /out be acomplished on the rear suspention... ??? And,,,, what the purpose of it would be,,,

 

The purpose is to tweak the suspension. It may not have the same range but the toe is adjustable as well as camber for the rear. It may not always sit as straight as you want it so there has to be some adjustability to it.

 

RIHI,,, at first i was a bit doubtfull about rear toe,,, then i found this info that supports rear axle toe,,,,, so i think u are correct.. , page 1 thru 5 talks about rear toe....this is interesting information ( http://share.qclt.com/bmw%E8%B5%84%E...%20Chassis.pdf ) also found this ,,,,http://www.bimmerfest.com/forums/sho...d.php?t=427949 and the guys are talkin about degree marks on the eccentric bolts for adjusting camber and toe...

 

I'm glad you found that thread.

 

I know the eccentric bolts, but were not aware of them doing toe-in/toe-out. While i'm still a bit skeptical on the whole "toe" issue, I haven't the time to verify it. I don't think one can achieve actual toe with simply adjusting eccetric bolts. If so, the yaw-rate sensors would pick it up and you'd have some serious issues especially if you have AS and DD.
To you is your car and to me is mine. Mine drives fine and that's all that matters to me. I have 10.5 inch wheels on the back and have never adjusted back because it's never needed it per Hunter Laser Alignment. To deal with the tire issue i do what I posted above.

 

I don't really understand what you are trying to say above. I merely said the rear suspension is capable of adjustments to both camber and toe (maybe minimal but capable). Whether your car needs it or not is not an issue in the discussion. Whether you use 8" or 10.5" wheels are not issues related to toe adjustment. If your car never needed toe adjustment, then that's well and good, but if other folks need an adjustment, it is there for them.

 

Me too actually, I'm not sure that toe in or out is an actuall process thats performed during a rear alignment..or if they even check for that,,maybe they do...Its possibly something thats adjusted during assembly of the vehicle for variences in parts... And not a neccessary adjustment,, unless the rear componants have been changed,, and allows to accomadate for differences in keeping the wheels parallel to the cars longitudinal plane ..As well allowing independent adjustment to maintain both wheel axles at 90 degree to the longitudinal centre plane.....