They say they are flattened and made of resin Ray
From the review
Accessory sets for these wheels offer upgrades such as flattened resin tires, photo-etched stem valves, and manufacturer’s name decals for the tires. These beautiful wheels are finished products by themselves, but you can still bring them even closer to reality with further artistic techniques such as chemical treatments.
Interesting is that the spokes look round, how the hell they achieved to mass produce those if not one needs to do that with wire ... there is a system I have seen done but it is a nightmare ...