Originally Posted by Joe@ApexRaceParts
A square set up will significantly reduce understeer on an otherwise stock car and greatly attributes to a more neutral handling car. The ability to rotate and work the car through the corner also becomes much easier when you have the same amount of grip in the front as the rear, in a square set up. Almost all BMW owners at track days and club races end up using square wheel and tire set ups (unless they have very high power levels) because of the control and ability to manipulate the car in certain ways are much higher when there is greater front end grip. It really comes down to everyone's different preferences with their own car and their driving styles.
Yes, true on the reduction of understeer, but at the expense rear traction. 1M needs the widest wheel/tire possible under the rear fenders to control the hp and tq coming out of the turns. The purpose is to give you the highest possible corner exit speed by getting back into the throttle at the earliest point in the corner as possible.
A better solution to understeer is more camber and a balanced suspension set-up.