You asked for Concavity? That's the 15x9 Miata 4x100 fitment:
Ultragram AT A GLANCE... (From KONIG Website)
The ULTRAGRAM is Konig’s NEWEST Flow Formed wheel and is the result of the most technology we’ve ever put into any wheel! We’ve taken every ounce of feedback we’ve received from all of our high level race programs to develop a wheel that will offer the most amount of longevity and rigidity all while offering an amazing weight savings. The ULTRAGRAM has 7-spoke, motorsport inspired design that is built with flow forming technology. The Ultragram has a knurl bead seat to prevent tire slippage for high-torque motorsports applications. Offered in both, Titanium Metallic and Carbon Bronze Metallic finishes with available sizing in 15×7, 15×8, 15×9, 17×8, 17×9, 18×8.5, 18×9.5A, 18×9.5B (select fitments), 18×10.5B, 18x11B with high and low offsets available.
Konig Ultragram 15x9 4x100 +35 - Titanium Metallic