Wheels of a bike is a shape of a circle.
Formula to find the circumference of the circle is:
c=πd Where c= circumference and d= diameter of the circle.
Given, diameter: d= 12 inches.
Now plug in d=12 in the above equation to get the circumference c. So,
c=π*12
=3.14*12 Since, π=3.14
=37.68
So, the circumference of the wheel is 37.68.