If its for a street car then whatever you get is going to be a compromise between weight and durability. For instance a set of drag specific race wheels are VERY light and save a huge amount of weight. In your case I'd go for something in 15" because there are heaps of tyres available in that diameter and will give you more options. Depending on how much street use the car would see I'd look at some BFG Drag Radials. A 15x6.5" rim will be plenty big enough to get a decent tyre on there for your purpose.