This study was performed to measure the extent of wear of unlubricated spur gears on the involute tooth. Contacts that roll and slide normally undergo wear. When material removal occurs due to surface wear from the gear profile, the surface pressure in the gear profile is redistributed. A mathematical model for predicting wear and wear pattern in spur gear has been developed. The prediction is based on wear-rate equation, load shared by the tooth in single-pair contact zone and double-pair contact zone. The distribution of the contact pressure was determined using the Hertzian cylindrical contact theory. For determining the sliding distance of the gears, the two-point observation method (TPOM) was used. Sliding distance at pitch point of gear and pinion was zero, because theoretically at pitch point, both zero sliding and pure rolling occur. The pin on the wear test method was used to obtain the wear-rate on the material and simplified to the time of measurement on the gear wear. Taguchi’s method for the design of the experiment was used, which significantly reduced experimental time with less experiment. Copyright © 2021 by ASME