If weight has no effect on lap times, why not just use any old 30 lb wheel? According to your referenced Modified mag article, having a heavier wheel would have a greater chance of DECREASING lap times if having any effect at all.
I'm positive that there is a difference between sprung weight and unsprung weight, so you comparing the 13.6 lbs of unsprung weight to the rest of the car (sprung weight) is flawed.