Many years ago (like 20) someone posted the exact PN for a 15x8 wagon wheel with the magic offset to work on a 40 series. It was offered by 4 wheel parts, but I don’t remember who actually made the wheel. Not sure why, but I think
@Mace and/or
@wngrog were involved in the discussion.
I don’t think backspacing is an issue with 16” rims as much, and 16x7 are almost always neutral.
If you’re interested in a really good deal on some 15x8s that will clear the 40 TR ends, I think I have a set that I took off a rig and put in storage…36 years ago!