Picked up a set of ronal r15's the other day that came with caps but no bolts to secure them to the wheel.

None of the wheel parts sources I've tried have such a part.
Ideally I would like to locate the original locking bolts with the keys but failing that I just want to be able to secure the centers.
Does anyone have any information that might help locate them, or happen to know the bolt specs? Today I'm just going to head to a fastener place and start test fitting but Its got an odd conical taper on the center cap but I can always modify it to work with other bolts.

None of the wheel parts sources I've tried have such a part.
Ideally I would like to locate the original locking bolts with the keys but failing that I just want to be able to secure the centers.
Does anyone have any information that might help locate them, or happen to know the bolt specs? Today I'm just going to head to a fastener place and start test fitting but Its got an odd conical taper on the center cap but I can always modify it to work with other bolts.