The meguiars hot rims works excellent but is EXTREMELY corrosive, it will eat painted calipers in seconds so do NOT spray calipers with it. I use simple green most of the time on my wheels since it doesn't harm much of anything but is still very powerful.
Go to the self car wash & wet all the wheels to cool them down. Spray the inside of each wheel (only clean one wheel at a time) with the Meguiars hot rims and let it sit for about 15-20 seconds. Then take the power washer, get up close, and spray the wheel down good - I guarantee this will work. Make sure you stay away from any painted plastic or other delicate surfaces with the power washer.
The power washer water pressure and the meguiars wheel cleaner works awesome together and will clean the most stubborn brake dust off the inside of the wheels.
Do ONE wheel at a time so you don't let the acidic cleaner sit on the wheels to long.
Once you get the wheels restored to new condition I suggest using a power washer and simple green as it is a less aggressive cleaner.
You will still have to hand wash the outside of the wheel to get it 100%. The above method will clean the dust off the inside of the wheel bringing it back to factory new condition in seconds.
Make sure you rinse each wheel thoroughly to fully dilute and wash away any remaining acidic cleaner.