L = 156m,

So, the perimeter of the tire = 156/39 = 4m,

So the radius of the tire = 1.13 m,

The diameter of the tire = 2.26m.

So, the perimeter of the tire = 156/39 = 4m,

So the radius of the tire = 1.13 m,

The diameter of the tire = 2.26m.