As standard the car is supposed to run parrallel from the factory, which when measured statically MOST Cossies do. HOWEVER, in forward movement, there is sufficient bush deflection that the wheels then toe out like this (both front and rear): \ / This wears the inside edges and causes the car to have some nasty fish-tailing lift-off over-steer.

The shims I sell give the car a small amount of static toe-in: / \ However, with bush deflection, this either gives the parrallel reading in forward motion or retains a small amount of toe-in which makes the car more stable in oversteer moments, as the car is always trying to self centre.

Unfortunately, the other 50% of wear is caused by the camber issues if the car is too low, or from squating under acceleration. The only way to remove this is with a fully adjustable rear beam.