B7 wheel/spacer/tire advice please

[Rae's A4]

I have spent hours searching this site only to come away more confused so please excuse another fittment thread.

I just bought an 08 white/tan A4 and would like to replace the stock 17" wheels and tires with a set of 18". The car has the factory sport suspension and i would rather not go any further into coil overs etc... like the look of the MMR GT1 or Petrol Vengance and from what I gather it seems that 235/40/18's would be the recommended tires to use. If anyone has any experience and can advise the proper rim width, offset and spacers if required please share. I definately want to avoid rubbing issues but really appreciate how much better your cars look with a wider stance.

Thanks in advance for your input.

[Doc@tirerack]

Normally we do 235/40R18 with a minimum load index of 93. Wheels we know to fit are 18x8+ and average ET32 to ET 45