When using non-stock wheels, please be aware that the Crossfire is hub-centric. This meant that the hub ring is what centers the wheel and the lugs just hold it on. Also the hub is 66.56mm diameter so the wheel center should be 67-68mm.


Many aftermarket wheels have larger hubs so one-size-fits-all (badly)


As to shim, in general you can go up to 3mm and keep the hub centered. Any larger and the shim needs a raised lip on the front to maintain the centering.


Some have had luck just using the lugs (acorn style), others have experience bad vibration. Have even heard of some running Ford (114.3x5) wheels on GM (115x5).