The ramps are 2X12X8 with mid supports being blocked up.
Again, it depends on species and wood is highly variable, but if it's clear white pine that sounds good for ~620# per ramp -- probably pushing your luck for that rig.
Now, if the ramps are southern yellow pine, then it works out to 825# per ramp.
[I think I made a math error originally. If there is an engineer in the house who feels inclined to check and make sure I actually have it right this time, here is the formula I used:
For:
C= load capacity
L= length of ramp segment between supports in inches
H= height of ramp in inches
W= width of ramp in inches
E= modulus of elasticity (~1,200,000 for clear white pine, ~1,600,000 for southern yellow pine)
I= moment of inertia (W * (H^3) / 12)
C= (L/128) x (48 * E * I) / (L^3) ]