motors/torque

[Mike Butts <buttsakauf-at-earthlink.net>]

I see all these hp ratings on electric motors and that is good for giving me an idea 
of what I need. My problem is that I do not know what kind of torque is needed to 
propel a 100lb tank at a decent speed. EV warriors are great but when they stall 
they draw huge amps. I have no idea what can really do the job. Would a hefty 600 
size motor be ok or is that too small. What about a 600 on a gearbox? I want a tank 
that can take on any surface and maintain speed (4-5mph??). I really don't know what 
to look for. 
Mike Butts