laborisfree said:
If there is any negitive effect I would perfer to forgo the exchange. Is there a source of 16.5 X 8" with the proper offset. The stock wheels are just a little too plain for my taste. I would like a five spoke aka grand sport.
Width and offset work together to place the outer/inner edge of the wheel/tire under the car properly. Offset is measured from the center of wheel.
The larger the offset, the farther under the car the 'center' of the wheel will be. So if the wheel is wider than stock, you may want it to have more offset so that it doesn't stick out. If the wheel is narrower, then less offset may be needed to keep the outside of the tire/wheel in a better position.
The early C4's can mount the 17x11x36mm on the rear without any problem while that same wheel sticks out on the late C4's (I know).
The Grand Sport's wheel is 17x11x50mm. It sits under the car farther. If you tried to use the GS offset 11" wheel on the 84, it would need spacers between the wheel and the hub to place it out correctly. Ditto for the standard 17x9.5x56mm wheels on the late C4 - spacer required to fit properly.
I guess what I'm saying is that the offset is just part of the equation. It goes with the width to make it all fit and work right. A wheel with 32mm offset or 38mm offset isn't the only consideration, unless you're looking at a wheel with the same 8.5 or 9.5 width as standard.
Since the wheels you are looking at are only 8" wide and have more offset, they will fit farther under the fenders than you probably want and may not look right on your car.
If they have tires already mounted, see if you can test fit one of them on your car and take a look.