[Derek Lecours]

Hi George and jtcb,
Now you are asking about cleaning the rims(Alloy wheels) and you are asking about cleaning the calipers on the brakes.

The alloy wheels are painted and clear coated aluminum.
Clean the alloys wheels with care. I use a weak solvent to remove the tar and road grease that sometimes spot the wheels and lower panels of the car body.
One common name used in Canada is varsol. It removes the grease marks very well but also removes any protective wax that was previously applied. I only use the varsol on the spots of tar or grease.

Do not use paint thinners because many brands are too strong and can easily damage the paint finish.
After removing tough tar or grease marks, washing with a name brand car wash will now remove the dirt and residue.
Now apply your favorite car wax:ie: Mothers Gold or Maguires or whatever.
Waxing the alloys(inside and outside) is a must in helping keep the brake dust to a minimum and makes cleaning them quite a bit easier.

Now to the calipers. I think the calipers are plated cast steel. The whitish color of the calipers is probably the oxidation of the plating and looks like crap.
You can scrub the calipers with a brush and clean them up and paint them with caliper paint for a better look.
Using a pressure washer can drive dirt into the piston edges and remove some of the brake lube that is applied.
I never ever use a pressure washer on my car. I hope others will add to this!!
Cheers, Derek