Groundloop
so the wing bending relief of the outboard engines offset the weight of the extra fuel.
Hope this doesn't sound picky but I thought that the "wing bending" that needed relief was generated by the lift forces on the wing. In flight this creates an upward stress at the wing/fuselage join which can be "relieved" by filling the wing with fuel. That either one or two engines are also fitted there is added relief not an "offset"