First, since the diameter of the tire is 18 inches, we can find the perimeter of the tire using the following formula:

we have that the tire has a perimeter of 56.52in. In feet, we have:

then, if the driveway is 200 feet long, then, dividing the length of the driveway by the perimeter of the tire we get:

therefore, the fewest rotations of the tire on the driveway is 42