In the fourth phase of the study, twenty-three coarse aggregates, sampled at the cold feed stockpile, are subjected to TCM, TCM with sand aging, X-ray diffraction, British Pendulum, Loss-on-Ignition, and chemical percent silica techniques. By comparing skid performance versus traffic (ADT, passes, and ESALs) with laboratory test results, aggregate performance and aggregate source variability may be categorized for effective use. Preliminary results indicate that the correlation between TCM and skid performance (R = 0.74) is far superior to the correlations between ASTM C 25 percent silica (R = 0.38), percent silica by X-ray diffraction (R = 0.36), and BPN 9 (R = 0.0004) with skid performance.