The radius at the equator is larger than at the poles because of the gravitational pull of the moon. Moreso the the fact that the Earth is roughly a sphere.
Right, but even so, my point was about the poles radius vs. equatorial, not the Arctic Circle, so my radius is that of the sphere, not the circles (Arctic vs. Equatorial). Another way to put my point is that the Meridians vary in size and shape depending on the location of the Moon, but they are just as likely to be non-circular because of the gravitational pull of the Moon which creates a bulge at the point where the meridians nearest and furthest from the moon at that time intersect the Equator.
Thus, not only is the Earth "flattened" at the poles, creating a shorter distance between a surface object at the poles to the center of gravity than the same object placed along the Equator (or any other point on Earth, for that matter), but that object at the Equator is frequently further away (due to the bulge) than most other points on the Earth, not just the poles. Between the Centrifugal force and the Moon's rotation (which are highly inter-related), together with the bulge & flattening created by those two forces, there is enough variance to conclude that the force of gravity experienced at any two points along the Equator will likely not be the same, and a comparison between said force at any point along the equator and a point at either pole will again likely yield different results.