The challenge has always been getting a brush into the narrow opening between the tire and fender-well. I have a cabinet full of tested and failed wheel-well brushes. Every available commercial brush - Including, the most resent suggestion, toilet-bowl brushes. Until now, I have been using the Speed-Master - With the unfortunate negative side-effect of scuffing. See attachment. Then, there is my newest pick… The cobweb duster-brush! No scratching, with the added benefit of an easy reach to the back of the tire.