I was at Bob Jane T-Mart in Kotara a couple of years ago and they had this whiz-bang doohickey computer thingy that lets you choose your car, then match available rims to it and part of what it had was a specification for offset (because spacers are illegal in NSW* and probably elsewhere). I'd suggest taking a stroll into a place like that and seeing what advice they can give, and who knows, they might be able to set you up with a good set of rims too. They do a good deal on Yokohama tyres now and again (I like Yokohama, quiet, good lasting grip, good longevity) - I bought a set "buy 3 get 4th free" so my tyre change was $750AUD.
* I spent some years working for a law firm and one of the cases they had involved a modified car that was involved in an incident that caused injuries for which the injured person was claiming insurance. It turns out this car had spacers installed and the claim ran into serious problems for the injured person, because now they weren't driving a roadworthy vehicle - and their insurance had a very clear "vehicle must remain roadworthy for the insurance policy to remain valid".
