Hi experts

Building a 4 wheeled cart to move materials and want to move cart with 2 dc motors driving two wheels. The 2 other wheels will be casters.I would like to be able to drive each motor seperatly so I can steer the drive wheels with power and possible running power driven wheel in oppsite directions to spin cart.

Max groos weight will be 10,000 lbs
Max speed is not a concern. 30 feet/min +-

The wheels will be 12 inch dia. Sprocket on wheel axcel to motor.

Any help on HP and sprocket sizes would be greatly appriciated

Thanks Bill