A study of the differences between the tire noise generated on the road and on a lab wheel was made using the “On-Board” testing technique. An Anechoic Chassis Roll facility was used for the lab wheel, allowing the use of exactly the same vehicle and microphone position for both tests. The only significant differences were the surface curvature and texture, and the absence of wind noise on the indoor lab wheel. Thirteen different carved designs were tested. There were basically three design types - rib, block, and lug - with varying void volume. The results of the study indicate there is good correlation in the more aggressive block and lug designs, but the quieter smooth and rib designs exhibit significant differences.