An equatorial diameter greater than the polar diameter makes the Earth this type of spheroid
In fact, that is actually the correct contribution that 
centrifugal forces make to... [DOC] [TLE] The Bulging Earth - MathPages [PAR] ... the equatorial diameter of the Earth differs from the polar diameter by about 1 
part ... We could make use of Newton's laws to predict the local plumb direction 
at ... of latitude would cover a larger distance near the poles than near the 
equator.