I just picked up an 1983 Alfa GTV6. I know there's a lot of talk about wheels on this forum. I'm looking at 18" wheels, Sport Wheels (SSW). They are model S039,18 x 7.5 ET38,73.1mm hub dia, 5x100 bolt pattern. It is my understanding that these wheels should fit the GTV6 with the use of hubcentric rings and wobble nuts. I'm a bit critical about using wobble nuts, and the wheel guys I use never even heard of them. In addition, the hubcentric rings they sell are plastic. Are the plastic hubcentric rings okay to use?