RS wheels are RS to clean.

[K1W1]

A rag and a bucket of soapy water worked best for me when I tried cleaning them.

[Antiplastix]

You must have really skinny fingers to fit between those narrow spokes. It took me just as long to clean the wheels as the rest of the car, and now its going to rain again. Grrrrr.

[woofy]

I used to always choose wheels that had broad spokes after my first car had painful alloys with little slots (80s these were around). I didn't get a choice with the RS, and while it could be worse, they are still hard to clean. These are the non Neptune ones.

[K1W1]

You must have really skinny fingers to fit between those narrow spokes.

Just poke the rag in between the spokes are around the back and out the front. a bit like drying your back with a towel.