Can you help me with a cleaning problem I have with alloy wheels? My process is rinse wheel first, followed by alloy wheel cleaner to the barrel and face of rim, then rinsed off, then a soapy mitt to go over the wheel again, then rinsed again. When I inspect the wheels when dry there seems to brown smudges left on the wheels, looking like I have missed areas but I haven't. Then when I use a cloth or my finger it comes off.