747-400 Overwing Fuelling Quantity

[NSEU]

Would anyone have any maximum fuel quantity/volumes for the overwing fuelling of 747-400 inboard main tanks? The refuelling ports are located at the inboard ends of the tanks and because of wing dihedral, the tanks cannot be filled as much as normal underwing pressure refuelling. I couldn't find a value in the Maintenance Manual (in Chapter 28 or Chapter 12).

Thanks!