Yes, you can paint or powder coat your wheels. However, be aware that the initial finish on the wheel is likely to be the most durable finish.
If you choose to refinish your wheels, we strongly recommend working with a local, reputable wheel repair / refinishing facility - a company that specializes in wheels is most likely to provide an excellent result.
Please also note that painting your wheels will also void any factory finish warranty, and in some cases, may also void the limited lifetime structural warranty.