This Z-tune fenders allow you to run a larger sized wheel and tire setup by way of being wider than the OEM fender. These also include a vent at the rear of the fender for the engine bay which increases cooling capabilities.
Please see the additional information beneath the pictures!
from the NISMO catalog:
“With an opening at the side of the engine compartment, the rear end of the fender has an air outlet design like that used in GT500. This efficiently discharges engine compartment heat and increases engine cooling efficiency while adding to down force. Because each side is extended by 15mm when using the fenders, wider tires (265/35R18) and wheels (18x9.5 +5) can be used.”