A robotic wheel gripper unit configured for gripping and transporting a wheel to a predetermined position; comprising: a selectively moveable arm ; and a gripper tool that is connected to a first end of the moveable arm ; wherein the gripper tool further comprises a plurality of gripper fingers having a top end mounted to platforms that are selectively moveable from a releasing position to a gripping position, wherein the gripper fingers are configured for selectively engaging a portion of a wheel ; and wherein the gripper tool further comprises at least one optical sensor that is configured to detect a location of a predetermined element on the wheel ; wherein the sensor is mounted to a sensor plate , the sensor plate extending downwardly from one of the platforms , and positioned rearward of the gripper fingers , between the gripper fingers , adjacent gripper grooves on the gripper fingers , that are configured to engage with the portion of the wheel when the gripper fingers are in the gripping position, to direct a beam of light to the wheel ,and characterised in that the sensor is configured to locate a tire pressure monitor system valve stem on the wheel , and in that the robotic wheel gripper unit further comprises a controller to which the sensor is operatively connected and that is configured to record the position of the tire pressure monitor system valve stem with respect to a fixed position and that is configured to control the gripper tool such that the gripper tool may position the wheel on an assembly conveyor in a predetermined position to locate the tire pressure monitor system valve stem at a predetermined orientation during an assembly operation with a tire. a selectively moveable arm ; and a gripper tool that is connected to a first end of the moveable arm ; wherein the gripper tool further comprises a plurality of gripper fingers having a top end mounted to platforms that are selectively moveable from a releasing position to a gripping position, wherein the gripper fingers are configured for selectively engaging a portion of a wheel ; and wherein the gripper tool further comprises at least one optical sensor that is configured to detect a location of a predetermined element on the wheel ; wherein the sensor is mounted to a sensor plate , the sensor plate extending downwardly from one of the platforms , and positioned rearward of the gripper fingers , between the gripper fingers , adjacent gripper grooves on the gripper fingers , that are configured to engage with the portion of the wheel when the gripper fingers are in the gripping position, to direct a beam of light to the wheel ,and characterised in that the sensor is configured to locate a tire pressure monitor system valve stem on the wheel , and in that the robotic wheel gripper unit further comprises a controller to which the sensor is operatively connected and that is configured to record the position of the tire pressure monitor system valve stem with respect to a fixed position and that is configured to control the gripper tool such that the gripper tool may position the wheel on an assembly conveyor in a predetermined position to locate the tire pressure monitor system valve stem at a predetermined orientation during an assembly operation with a tire. <EOS>