It's apparently not RONAL since their website states:
Ronal manufactures wheels for most of the automobile manufacturers. Companies like Mercedes, Audi, Porsche, Saab, VW, Rolls Royce, Lotus, Toyota, Nissan, Honda, Mitsubishi, GM, Cadillac, Ford, Suzuki, Skoda, Seat, Renault, and Votex are just some of the manufacturers who rely on the timely delivery of their quality alloy wheels.
Specialty European tuning houses like Lorinser, Alpina, A.C. Schnitzer, Carlsson, Brabus, Hartge, Steinmetz, Nothelle and others, who specialize in the 17"-20" market share, rely on Ronal's leading edge technology, creative design and uncompromising quality.
Interesting that BMW isn't a listed customer, but that Alpina and Hartge, the two major BMW tuners are. Of course MINI is not affiliated with BMW, so who knows?