In that case, I vote white letters out. Black car, black tires, black wheel opening around the tire... the white will break up/fill in that expanse of black a bit.
My wheels were pretty once, as were the tires, the day the tires were installed. I haven't paid much mind to 'em since because they work toward the overall look I want: the neglected high-school beater.
Two things nobody expects: 1) The Spanish Inquisition. 2) A crappy-looking old Valiant with a solid-roller W2 340. :D