Answer
$x^2+(y-139)^2=125^2$,
Work Step by Step
The diameter of the wheel is $250$ feet, thus the radius is $250/2=125$ feet. The maximum height is $264$ feet, thus the height of the base of the wheel is $264-250=14$ feet. Thus the center is at $(0,14+125)=(0,139)$
The general equation for a circle with radius $r$ and centre $(h,k)$ is: $(x-h)^2+(y-k)^2=r^2$, hence our equation: $x^2+(y-139)^2=125^2$,