I had a Boars Hair brush that would not come clean with anything I tried. What did work very well was pouring Persil laundry detergent on the bristles
Rim cleaning made easy Kärcher International
Tradition Los Angeles lifestyle. Scrub Tires Clean: Scrub dirt and grime off your tires with the Big Blue Stiffy! The stiff bristles scrub hard to remove dirt, grime, tar, and other stuck-on road debris that gets baked into your tires and that other brushes can't budge. Restore Sensitive Carpets: Reach deep into carpet fibers with the big Blue Stiffy Brush! Each one of the stiff bristles works it way deep inside the fibers to loosen and then lift up embedded dirt and grime for easy removal.
Chemical Guys Big Blue Stiffy Tire Brush, Heavy Duty
Ultimate Wheel Cleaning Guide: Techniques, Products, and Best
Page 2 - GRIP Cleaning
Tire Brush, Stiff Bristle Wheel Cleaning Brush, Car
White Lightning - Easy Clean Tire Brush™
How to Clean Your Tires (Stop Using These Chemicals!)
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Detail Factory - Progrip Tire Brush - Ergonomic Progrip Handle, Stiff Synthetic Bristles, Ergonomic Design, Clean Your Tires with Ease, Grey
How to Clean Tires - The Home Depot
Car Washing 101: 7 Rules to Follow on your next Detail – Leno's Garage
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Wheel Brush: Types, Uses, Features and Benefits