Well, I don't want to be on the wrong side of PEInc, for whom I have great respect.
I do not believe a simplified active wedge accurately captures the actual strain behavior of the soil mass behind a partially restrained wall with repetitive high magnitude wheel loads. Lateral load is dependent on the wall system stiffness. Not all cantilever walls behave the same.
For a simplified Ka calc using phi = 34 degrees, Ka = 0.28.
For moist soil wt = 120 pcf, the pH = lateral earth press = 34 psf / ft + Ka*pv. That's too low, and I'll stand by that claim.
For comparison, consider two cases.
a. Caltrans pH for culverts = 100 psf / ft. [Section 6]
Caltrans, albeit a politically flawed institution and known for conservative provisions, does have a few smart engineers, and their engineers have made many edits to their Bridge Design Manual for several decades based on lessons learned.
b. Pressures for compactive equipment. See Terzaghi Peck Mezri Article 44 and 45. I do realize that compactive equipment is not the same as repetitive wheel loads. However, it does provide some insight on the wide spectrum of actual lateral pressures behind walls, based on non-static loading.
Do you want to choose the very lowest static pressure (Ka < 0.3) for a wall that will have compacted backfill, then dynamically loaded for the next 50 years?