These similar posts keep coming up a lot lately. Trust me....use a 2" medium paint brush and silicone tireshine. It's immediately take away the white, makes the black plastic look awesome and the brush makes is super easy to get shine on the fender flares w/o getting it onto the paint. I also use the brush to do my tires also so I don't get overspray onto the body. Just squirt the silicone from the top of the tip and start applying. I have a loose fitting ziptie around the neck of the silicone bottle so I can keep the brush w/ it at all times.

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