Hello Mr.Tech
I have thse wheels an they are matched set with off grey in color from the factory, an I noticed the valve stem hole is oval
shape ,I am debating to sell the wheels to good home ,I need going estimated value. I need expert assistance. THZX Joe

The mfg date of the wheels is next to the air valve stem.......starting with K 1

The early 70 Z-28's had 5/8" X 1" holes , but changed to 13/16" x 1" around May 1970.

The 7/8" ROUND (clearance) hole wheels started with the 77 Z-28 and increased to 1" in ?????. There is ALL this info at www.nastyz28.com IF you the patience to look.

You would have to watch EBAY to check for values........Any oblong hole wheel is much more valuble than the round ones......

Dates are covered by trim rings, and nobody ever sees them............

I have seen the early valve stem hole which Chuck has mentioned sell for $200 a piece. It all boils down to the date and condition of the wheels. The earlier the date, the higher the value. If your 4 wheels are a dated set, they will also be more desireable.