Answer
$(x-0)^2+(y-139)^2=(125)^2$.
Work Step by Step
The diameter is $250$feet, hence radius$=d/2=125$feet.
Maximum height$=264$feet, hence thei height of the wheel base is: $264-250=14$feet.
Hence $C=(0,14+\text{radius})=(0,14+125)=(0,139).$
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: $(x-0)^2+(y-139)^2=(125)^2$.