Diagonal wear on tires is a significant problem that can cause noise and vibration, and reduce the useful life of the tire. A wear model is used to show how diagonal wear can develop across the tread under certain conditions of toe and camber on a nondrive axle. In a simple wear model, tread wear is taken to be proportional to abrasion and sliding length. Triaxial stress measurements made in the laboratory on the tread blocks of rolling tires provide data for the wear prediction model. Under nonzero toe and camber the magnitude of the predicted wear is increased and its pattern becomes diagonal; a higher wear rate is predicted near the leading edge of contact on one side of the tire and near the trailing edge on the opposite side. This prediction agrees with the diagonal wear pattern seen on tires run on the road at similar toe and camber settings.