This is a robot drive wheel we had made specifically for us. It does not have a bearing. Its 6 inches in diameter. 1.9" inches wide. Its a rubber pneumatic tube tire. The rim has a 4 bolt pattern so you can easily mount it to a flanged hub.
This is a 4WD IG42 single bearing platform that is setup for outdoor navigation/positioning. A full array of sensor options including an IMU, motor encoders, and a Garmin 18x GPS that can provide position feedback with up to 3 meter accuracy.