Hey I'm about to buy these rims but I don't know if they will fit my car. Please help!
This is what I drive: 2003 Infiniti g35 coupe (non brembo) I currently have the stock 18"s on there)

Here's the link to them :
http://m.ebay.com/itm/400783280031?nav=SEARCH

Here are the demensions:

Model - ADR M-Classic

Size - Front: 20 x 8.5 / Rear: 20 x 9.5

Bolt Pattern - 5 x 114.3 ( 5 x 4.5 )

Offset - Front: +20mm / Rear: +25mm

Hub-bore to fit - 73.1mm (Bore may be larger - may require hub-rings* )

 

They will fit but they are very cheaply made wheels, I'd reconsider the purchase.
You will find most people on here are all about the forged, multi-piece wheels and they have a point. Those brands are amazing quality but they also come with a huge price tag, you pay for quality right?
Keep your eye out in the marketplace here for a quality used set, and avoid brands like XXR, MSR, ADR,...just some advice.