(Note: I don't understand why Creality Cloud show the bottom of the wheel on the blue picture automatically from .stl file)
My Decathlon ping-pong table wheel broken down (see outdoor prototype picture). This is a more rigid version of those gear.
External diameter 15cm, width 3.5cm, hole for M8 bolts (exactly 8.4mm to have free play).

I recommend to use ASA material due those UV/weather proof and also high temperature resistance. I used vendor Formfutura product ReForm - rApollo due those have only bed temp 80-100C and head temp 235-255C which is supported by my Ender-3 V3 KE and also relative cheap due recycled material. Be care lot of ASA materials above the

100C temp range which not support be general 3D printers.

Infill settings important not just for the rigid structure but also for the support free printint! See attached picture the infill must be reach the edge of the circular shape on the layer 112 (if you use 0.2mm layer height). I used Grid 10% or 15% filling without any issues.

Bottom side is flat to have good build plate adhesion and able to print support free.

The bottom side of the gear not nice due overhanging but due dual gear design those not visible (see outdoor prototype picture) due inside but that is the only way to create support free in FDM.