It is advisable to measure any pulley wheels (grooves) in the system that the new rope is going to pass over (including deflector pulleys).
A new rope can easily be damaged if the pulley wheel groove is too tight, this will in effect pinch the rope probably causing a wave (spiral) deformity in your new rope.
If left unchecked in a steel pulley, parallel, linear fatigue wire breaks will be found where the contact pressures have become too high, due to a pinch affect.
The diameter of the new rope will be larger than the one to be removed. The old rope will have worn the groove material to the worn rope diameter.
We recommend a clearance of 10 to 12.5% above nominal rope size for steel pulleys and 15 to 20% for polyurethane or other types of lining inserts.
Ideally the pulley wheel groove should support 120 degrees or approximately 33% of the rope circumference.
Defector pulleys should contact the rope at 15% of the rope circumference.