The yaller, space-saver rims were only used early in the '78 production run, up until around the last of the Pacers. After that, black rims were installed.
The story is, one of the higher ups in GM/Chebby was driving a Pacer when it had a flat. When he stopped and put that bright yaller spare on, he was quite embarrassed... It just wasn't right for him to be driving a Corvette Pace car, with such a goofy lookin rim!. So...the rims were painted black. The original intent of the yaller rims was just that...so the folks that had flats would get them fixed quickly(before anyone saw them!), and not run that small spare tire for extended periods.

All Corvettes after the '78 models will have the small spare. I'm not sure(without looking at my references) exactly when they started using the space-saver tire/rims, but it was in '78. Perhaps Tom (hunt4cleanair) could, once again, confirm this, and a time-line.

I have the original spare tire and wheel also. Never used

That original air ought to add quite a few points for NCRS, right Joel?

Only if there is documentation that it is, in fact, St. Louis air, Dennis...I've heard tell of a few judges that can tell by smellin the air in the tire, but...that may just be one of them there "Urban Legends"...

If'n it smells like hops, barley and rice, it should be St Louis AIR!!!

yes, 1978 is when the smaller spare was started to be used because o of the bigger 25 gallon gas tank put in them.
bob