It's not a wheel clearance issue; it's a tire clearance issue.
215/35-18 is about as big a tire as you can put on the front of the NSX and be pretty sure it won't rub. Any bigger size tire has a good chance of rubbing.
The problem is, 215/35-18 tires are usually only approved for mounting on wheels that are 7.0-8.5 inches wide. So 18x9 is too wide for a 215/35-18 tire.