For anyone just tuning in, this was first brought to market by BMW a few years back.
This is an example of a Coanda Nozzle, taken in a wind or water tunnel:
In this case the rounded surface is the shoulder of the tire.
The size needed is really small. I'm collecting parts for air curtains for my car. It was going to 3 or 4 times this size, and have a shark fin added outside the stock fender to put the air past the face of the tire. It looks like on the Ford truck the outer half of the tread is the target.
Any guidance on this? Maybe I'll just stop by a Ford dealer.