on the streets, it's all about styling. Racing, it's a totally different story.
First, you want a rim that is light. There's heaps of diff in using a heavy rim as opposed to an ultralight rim that a company such as BBS and the likes churn out. THis is mostly on track though. Steering feel can actually differ. Also, you need a rim that can withstand bumps well, but also collapses easily enough during impact.
On rally cars, you'll mostly find those whhite rims with lots of spokes and a disc in the center. This design makes the rims much heavier, but in a rally, lil differences in rim weight is minimal. However, the inner rim has a significant role. Rally drivers are human, and they crash heir cars time to time. The first thing to go are usually rims.
The spokes might all break off, taking the whole tire with it, but the disc remians attached to the axle. The inner disc allows the car to limp to the next designated service stop.
General ruleof thumb, rally rims are somewhat heavier and stronger than rims designed for track use.