Martin is cleaning the tires of his bicycle. He notices that his bicycle tire has a radius of 8 inches. How much bigger is the area of the tire, than the circumference

Strange question, as normally we would not calculate the "area of the tire." A tire has a cross-sectional area, true, but we don't know the outside radius of the tire when it's mounted on the wheel.

We could certainly calculate the area of a circle with radius 8 inches; it's

A = πr^2, or (here) A = π (8 in) ^2 = 64π in^2.

The circumference of the wheel (of radius 8 in) is C = 2π*r, or 16π in.

The numerical difference between 64π and 16π is 48π; this makes no sense because we cannot compare area (in^2) to length (in).

If possible, discuss this situatio with your teacher.