I think those style of wheel covers do two things.
1. They are aerodynamic.
2. They cool the brake via turbine fins
PLUS
3. When the front wheels cut for a turn they are still doing all of the above - the rear wheels stay in plane with the body however.
The rear wheels also get cooling via dedicated ductwork typically in high performance cars.
An example below of turbofan wheels from the early 1980's...
https://www.jdmeuro.com/tag/turbofans/
Jan 2019
Turbofan wheels do more than just look good
https://www.hagerty.com/articles-vid...just-look-good
Quote:
In terms of ‘70s/’80s racing ephemera, turbofan wheels are rare air. Turbofan wheels, named after the jet engine, were conceived as an aerodynamic boon.................
Managing tire and brake temperatures on a racecar is an exact science. Both need to be kept warm without getting too hot. As modern disc brakes grew larger, more complex (vented, slotted), and more powerful, overheating became an issue. Good brakes are the difference between victory and an inglorious crash into a tire barrier. And with brakes, the right temperature is key: Cold brakes can’t stop as effectively, hot brakes lead to fading, and overheated brakes are downright dangerous. But getting tires and brakes up to operating temperature quickly is also necessary, especially in qualifying, where time is a constraint.
Turbofan wheels work to passively pump air inside the wheel toward the brakes. The outside covers direct fresh cooler air inward. Perpendicular louvers underneath the cover guide the air directly at the brake rotors. Ambient air moves faster over the outside cover than the hot air inside, and the low pressure generated by the outside air draws the hot air out.
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This is interesting....................
Quote:
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Eventually, turbofan wheels were banned by most racing series, deemed “moveable aerodynamic devices.” Rumor has it that some wheels were designed to evacuate air from the entire bottom of the car, thereby increasing downforce.
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I think from a marketing viewpoint, too many aero-treatments make the car look fussy or delicate, and not very macho. If only 1/2 of the car has aerodynamic wheel covers, the people that want none of it, and the people than want them on all four may be able to live with it, hence a wider audience acceptance.