White stripe tires so they could be winter tires!
KURT they are WINTER TIRES... look at the leading edge of the tire where it runs off the photo... mud and snow.
REGARDING the RS/Z - it also straight bar headrests and a narrow spoiler ie early car. -I also see it has a RS emblem in the grille as well as the Z28 emblem - Z28's were dual marked on the side of the car front fender carried both - possibly also on the grille in the beginning of production?