You'll find several existing threads here on which wheels fit.
Also, I've looked on Craigslist for wheels but sellers seldom provide the specs. Fortunately, there are several good sites that provide original wheel specs for thousands of cars so you can cross-reference those specs to the Leaf specs. Here's one such site:
For your Leaf, if you want 16" wheels then these are the specs you need to match:
Wheel size: 16"x6.5" (7" wide aluminum alloy wheels are OK too)
Bolt pattern: 5 x 114.3mm (this must be exact)
Offset: 40mm (positive)
Center bore: 66.1mm
Any wheel matching those specs should fit and anything close to those will likely fit too. Note that a lower offset will provide more clearance for the brake calipers, so should be OK.
This site helps too:
Before buying any wheels, mount one on a front hub and make sure it fits.
Vancouver, CA owner of a 2013 Ocean Blue SV + QC, purchased 01/2017 in WA
Zencar 12/20/24/30A L1/L2 portable EVSE
1-1/4" Curt #11396 hitch
After market, DIY LED DRLs
LeafSpy Pro + Konnwei KW902 ELM327 BT OBDII dongle
Loving my first BEV