Standard leather wrapped wheels start with a tubular steel frame (not a flat frame like a MOMO). Then the rubber core molded over that. Then leather wrap. Nothing between the leather and the rubber.

As for the sport 380s, as has been shown several times, the ebonite core has a felt wrap and then a soft cotton mat (not woven) and then the leather. I highly doubt a leather wrap directly on the ebonite as it would have a tendency to shift.