We study the configuration and wall collision process of a wall tethered polymer in shear flow using a Brownian dynamics technique. We develop scalings based on the flow strength and polymer length to explain the nonequilibrium polymer dimensions and wall collision rates along the polymer backbone. Our simulation results corroborate this theory and collapse under these scalings. For the first time, previous experiments conducted with DNA molecules showing the strong dependence of polymer dimensions on length are successfully compared with simulations. Our results highlight the connection between the tumbling of a free polymer and the collision process of a tethered polymer. We successfully describe the chain collisions as a Poisson-like process, where we observe that a minimum number of wall collisions is experienced by the segment located at approximately 3/4 the distance along the polymer backbone from the tethering point. Our bead spring model captures all the essential physics. Hydrodynamic and excluded volume interactions are included, and we use a recently developed force law which accurately models worm-like chain behavior. Additionally, a successive fine-graining method is used to minimize the effect of using a coarse grained model.