I don't think any replicas are made in that size. FVD had some japanese cast Fuchs replicas, but only up to 8x15.
Considering how hard it must be to find tires in the correct size for 11x15 Fuchs they can't be *that* sought after? There must be some for sale somewhere? Actually I think I just read about some on
www.elfertreff.de (911Forum).