The direction in which the spokes are running. The wheels were designed to actually "pull" air into the wheel past the brakes to help cool them. Your back wheel is on correctly. The spokes should point forward. The one on the front in the picture the spokes are pointing toward the back.
Depending on the tires, it might be as simple as swapping the front tires around. If they are directional tires, they will have to be dismounted and reversed to be corrected.
The other factor would be if you have TPS (tire pressure sensors) they may have to moved from wheel to wheel. TPS wasn't all that common in 1990 unless you have a ZR-1, then, if I'm not mistaken, all had TPS.
Car is a 2: owner originally purchased in Pittsburg. It spent a year there and came to Ft. Lauderdale, Fl as a "Winter Car". It currently has 70K miles and is driven mostly to clocal car shows and Corvette Club meetings. We are members of the Corvette Club of Marion Co. Florida in Ocala.
I bought this one after I wrecked my '94. This one is in much better shape than my '94 was (before I wrecked it).
I have an unrelated question as well..... Does anyone use a different type of oil instead of the Mobile1? I refuse to use ExxonMobile products and want to use something different. Would any type of full synthetic oil be OK?