Heavy duty robot wheel with traction lug Tiller tread. It does not have a bearing. Size: 3.5-4. It's 10.5 inches in diameter, 3.5" inches wide. Its Pneumatic with a 4 bolt pattern so you can easily mount it to a flanged hub.
This is a MLT-JR tracked robot platform and is equipped with 32mm motors, a motor controller, and Spektrum remote control. This robot is a prebuilt version of TP-220-001, and can handle up to 10lbs of additional payload/speeds up to 85 feet per minute.