C4D has an upper limit of 16,000 pixels in both directions, but a still image, at that size, will take a very long time to render, on a single machine.
Here is the link to a tutorial on setting up a "Tiled Camera" for rendering large stills, in C4D.
This tutorial shows you how to break a single-frame into "Tiles". Each tile can be rendered on a separate render-node, allowing multiple render-nodes to work in parallel, on all the tiles.
Prepare the Scene File for Tile Rendering
Tiles Per Axis / Frame Range
The "Tiles per Axis" will vary depending on how complicated/large your scene file is. A value of 2 will output 4 square images. A value of 4 will output 16. This works in a X * Y grid, so 4 tiles on the X-axis and 4 on the Y-axis. (4x4=16 or 2x2=4). The frame range you choose will depend on this. If you use 4, that's 16 tiles, so your frame range will need to be set from 0-15. A value of 2 (4 tiles), then your frame range will be 0-3. (Frame 0 counts as the first frame). Once the tiles have been completed you will need to download and stitch them manually in Photoshop. Unfortunately C4D does not have a feature to do this manually.
Submit Your Render