Now that an authoritative answer has been provided, I will ask another question.
Q1: Why do people like the the appearance of these trucks?
A1: The fat fenders.
Q2: Why do larger people like to wear dark or black clothes?
A2: To make them appear more slim.
Q3: Why do people like the appearance of black truck fenders?
A3: The fenders appear less fat??? Not logical. Conflicts with answer 1.
So why paint the fenders black?
