I had a Gran Marquis with the small spoke wheels, could be tough.
They would get dirty, but since the car was washed once a week, never any real build up.
I would usually just mist them with water to make sure they were cool and then spray with an all purpose, and use a "round pastry brush", they are like a "parts brush" but softer bristles.
Could quickly stick it in the spoke area, a slight twist, and such until done, then rinse off.
A lot of times the all purpose and some water pressure would take care of them with no brushing.
If really bad, like from one of my two week, driving on business to the east coast, would use the ValuGard Custom Wheel Cleaner, let it dwell for a few minutes and pressure off with water, that really got them clean. (safe product, that they private label for several of the automotive manufactuers)
Grumpy