If you have not already seen it, you might consider the "Dagu Rover 5 Tracked Chassis with Encoders. Otherwise, I do not have any additional suggestions for a chassis in that size range.
If you make your own chassis, the specific wheels, motors, and controllers would depend on the size and weight of the robot you are building. You might find our “Force and torque” blog post helpful in deciding how much torque your motors will need for your robot. We generally recommend choosing a motor driver that has a continuous current rating equal to or greater than the stall current of the motor you choose.
If you determine what size and the torque you need for your robot, I would be glad to help you choose a motor and controller pair to match those specifications.
If your motor’s output shaft is a 3mm D-shaft, you would not need any adapters. If you have some other output shaft, you can see our selection of aluminum mounting hubs here.
Please note that the 1/4" mounting hubs only work with our larger 80mm and 90mm wheels.
You would need our universal aluminum mounting hubs for 4mm shaft to adapt those wheels to work with the Dagu Rover 5 chassis. Please note you will also need some 4-40 screws as we mention on the hub’s product page.