New to RC and need help figuring out what servo I need

[archemedes]

New to the forum so I hope this is the right place for my request.

I am building a large RC "Vehicle" for a Maker Faire in my town. But it won't be a car, per-se. It will be an entertainment center with a television in it. I have roughly estimated that it will weigh about 250 lbs. My problem is finding a servo to drive the steering on the front wheels. I am unsure how to calculate the torque required to turn wheels under that pressure in a reasonable amount of time. I am trying to do this as cheaply as possible so I don't want to pay for more power than I need, but I also don't know where to begin. So with that in mind, does anyone know how to figure out the torque required, and also if possible a motor that would fit my needs? I'm sure you'd need more variables for the device, but I am not yet sure what is needed, so if you want clarification ask away.

 

[robmob]

With that much weight I would do what the battlebots rigs do and use a tank style steering system.

 

[Rolex]

The absolute minimum I would consider would be a 1/5 scale steering servo.