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 set of wheelchair motors and make great heavy duty robot motors. One left motor and one right motor. They are right angle gear drives with a release and electric brakes. They are 24VDC and the operating speed is 120 RPM.