Question 183306
Let d=diameter of the earth and C the circumference.
C=pi*d 
The diameter would increase 36' (18*2)
C=pi(d+36)
The circumference would increase pi(d+36)-pi*d=pi*d+36pi-pi*d=36pi
This is 113.09... ft irrespective of what the diameter
Only 113' more wire would be required.
The same amount would be required on the moon or on Jupiter (if it were rocky).
.
Ed