If a wheel is 8" wide and has 0 offset, isn't that the same as a 4" backspacing?

I'm looking at 16x8 wheels with a 0 offset. I'd like to run 255R50-16s on my '68. Any issues with that?

It depends on where you measure the backspace from. An 8" wheel is 9" wide lip to lip. The 8" dimension is measured where the tire mounts. So the true backspacing would be 4.5".

KAA is correct
an 8 inch wheel is actually 9 inches wide. It has to be about one inch wider than advertised to allow the tire beads to be separated by 8 inches.

Offset is measured from the center of the wheel and back space is measured from the back edge of the rim. So a 0 offset 8 inch rim (which is actually 9 inches wide) will have about 4.5 inches of back space.

Clark,

How goes it there at Mother Rucker these days?? I retired from there 2 years ago... Was the Operations NCOIC for the Safety Center and lived out in Enterprise. Have you ever been to one of the Cruise nights out at Sonics?? Don't think that they have started yet for the year but should be soon. You can find out more about it if you contact Don Solesbee thru Enterprise Computer Store.