What are the lowest legal sized rear King Springs for a Holden VS Wagon?

I've been asking around and people are having trouble with getting back to me with an answer. Im looking at lowering my VS Station Wagon with a set of rear King Springs. I'm curious to know if ANYONE knows what the lowest LEGAL springs are called. Are they called Lows or Super Lows???? I know you need to be able to fit a coke can under the lowest part of your car for it to be legal, the thing is i dont know what springs will be perfect for that. Someone help me out here???