Hello Will,
So, with regards to my local knowledge, this stretch of the CA 180 funnels significant amount of traffic from Fresno towards Sequioa and Kings Canyon National Parks. CA-180's expressway has only recently been extended to bypass the village of Centerville and the hamlet of Minkler in order to prevent traffic from backing up in those localities. The J31 road (South Reed Avenue) does drain a significant amount traffic southward to the City of Reedley. I would prefer that CA-180 be marked as trunk all the way to this junction and at minimum the road should be marked as highway=primary and Expressway=yes not farther west than North Academy Avenue (the major north-south throughfare that  runs between CA-168, CA-180, and Sanger. Let me know what you think!
Sincerely,
Fresnomap 