as a general consensus in the industry the V shape is the old way of doing things. Once they got really serious in wind tunnel testing and such they found the U shape to be better. Now everyone’s adopting the U shape more or less. Usually the U shape rims are being made wider too which is a benefit.
With a V shaped rim, the front of the wheel with the tire on it makes a nice streamline airfoil shape…but…the back half of the wheel has the sharp edge forward, so makes a backwards airfoil. The blunt inner edge of the U shape provides a better compromise drag-wise and also makes the front wheel less susceptible to being deflected by crosswinds.
tire to rim interface is the biggest thing in terms of aerodynamics. A lot of people are running the Conti GP4000 in the wind tunnel because it shows good results. If you switched over and used a Vittoria the drag graphs would look completely different.
Brand new tires actually test way faster at higher yaw angles compared to a tire with just a little bit of mileage on it. From 0-10 degrees yaw, the graphs were identical, but then the slightly used tire got WAY slower.
