I don't believe there is any further clarification needed about the wheels. The Sept 2019 GCR has an update..
Section 9.1.1 Formula Vee Specifications ... page 249.
C. Wheels shall be standard fifteen (15) inch X 4J as used on the 1200cc and 1300cc VW sedan as
defined herein, or any steel fifteen (15) inch X 4.5J wheel within the track dimensions of C.2. Wheels
may be balanced only by the use of standard automotive balance weights (adhesive or clip on). Hub
cap clips shall be removed.
emphasis mine... This would obviously include 4 bolt wheels - as long as they are
1). Steel
2). 15 inch rim diameter
3). 4.5 inches wide
4). The car meets the track dimensions after installation.
Steve, FV80