I wash the wheels with warm, soapy water. This is the same auto soap as I use on the car-( Ice or Mothers ).
I ignore the calipers and the most attention they get is a rinse with the water hose.
My calipers look OK - they look like cast aluminum.
I would never use a high pressure washer on any part of the car. High pressure tends to drive the dirt particles into the clearcoat paint - which is exactly what I do not want. High pressure directly on the brake components is also not recommended - you could soak the pads and reduce the braking effect or damage or destroy rubber hoses etc. If you cannot resist using your pressure washer on something, use it on the concrete driveway surface.
