none of the tested wheel cleaners did a better job than a less-expensive all-purpose cleaner. The one we tried, Zep Industrial Purple Cleaner & Degreaser Concentrate, is available at home centers ...

Cue Zep, a grout cleaner and brightener ... Then I squirted Zep directly onto all the grout lines, no brush needed at that point. Zep recommends application to grout lines only, so I tried ...