So for those that are interested, i spoke to customs today and any wheels that are sourced and manufactured wholly in the USA are a scheduled item under the Australia - USA Free trade agreement and are free from any duty charges.
I basically paid the $55 dollar fee to an agent, got the supplier to fill out a declaratation and the wheels / tires will come GST / Duty free! Which makes the purchase price very appealing once again. If anyone wants more info PM me but it's a fairly straight forward process
