These are snap-in Nissan Leaf wheel cover plates (aerodynamic mod).
This Nissan wheel-cover has two unique shapes - small and large. You can install both types for complete aerodynamic coverage, or stagger them.
For best results print vertically one part at a time. I intentionally over-extrude in spiral (vase) mode with some brim. I'm using 0.3mm layers and a 0.4mm nozzle with line (extrusion) width set to 0.7mm in Cura:
Spiralize Outer Contour - checked
Smooth Spiralized Contours - checked
For multiple parts at a time, just be sure to align your seams with the end of each flange (away from the exterior surface). This will preserve the retention clip strength and maintain a nice looking outer surface.
I'm using Hatchbox ABS, but PLA or PETG would probably work just fine.
Snap the parts in, and make sure they are secure. To access the tire valve, I simply remove the entire wheel cover. Consider removing the wheel covers to allow for brake cooling on very hot days and/or if you plan on long descents, etc.
Aerodynamic assessment using coast-down testing methods are planned in the near future. In the meantime, development of this design is based on the aero data from this study by Alexey Vdovin (specifically, configuration "f"): https://core.ac.uk/download/pdf/70600281.pdf
This design was inspired by similar alloy wheel Nissan Leaf Petals by Paul Kennett: https://www.myminifactory.com/object/3d-print-nissan-leaf-allow-rim-area-inserts-76399