For one-CIM-per wheel:
amps=(5760*Istall*mu*V*W)/(pi*eff*Sfree*Tstall)
or
V=(pi*amps*eff*Sfree*Tstall)/(5760*Istall*mu*W)
where:
amps = current required to slip the wheel
Istall = CIM spec stall amps
Tstall = CIM spec stall oz_in
Sfree = CIM spec free RPM
mu = static coefficient
V = robot ft/sec speed at CIM free RPM
W = weight in lbs on the wheel
eff = drivetrain torque efficiency fraction
So, plugging in Oblarg's numbers:
amps=(5760*133*1.0*25*40)/(pi*1.0*5310*343.4) =
133.7
You're not going to get 133.7 amps in each of 4 motors, so if you gear for 25 ft/sec you definitely will not slip.
Let's try some more reasonable numbers and try again:
mu=1.0 V=12 W=37.5 eff=0.8
amps=(5760*133*1.0*12*37.5)/(pi*0.8*5310*343.4) =
75.2
Will the wheels slip? Well, 75 amps per motor times 4 motors is 300 amps. If your battery is strong your wiring is in good shape and the CIMs aren't too hot you might be able to push 300 amps thru the 4 CIMs.
Let's try V=10:
amps=(5760*133*1.0*10*37.5)/(pi*0.8*5310*343.4) =
62.7
OK, maybe that will slip.