The "ledge" you refer to is there to align and centre the alloy wheel on the hub . A large proportion of the torque and load carrying is taken by the clamp load (friction) between the wheel and hub . the bolts should not take much shear, neither the ledge. A hub with no ledge uses the taper on the bolts/nuts to centre the wheel, and the load is taken as I said between the bolts and friction . Most steel wheels do not centre on the hub centre but again on the taper of the studs/ nuts.
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