Hello!
[tex]\large\boxed{\text{D = 255pi in or 800.7 in}}[/tex]
Solve for the distance by solving for the circumference of the wheels:
C = 2rπ
C = 2(8.5)(π)
C = 17π
The wheels make 15 rotations, so multiply the circumference by 15:
17π × 15 = 255π or ≈ 800.7 inches