I would like to put some RX8 wheels on my 1990 FC. I have stock suspension. What wheels will fit and with which tires. What will I need to do to make them work? Not looking to roll fenders.

 

Start with reading here:

FC3S Pro v2.0: Mods - Rims

 

Just my two cents, but... RX-8 wheels just don't work right on RX-7s and look pretty chunky. You may need spacers to clear the calipers and front springs since offset is at -50 and width and height are also going to be over an inch more. Also remember the diameter of the RX-8 wheel is bigger compared to any stock sized wheel which effects speedometer/odometer readings and fitment.

205-60-15 = 24.68" overall diameter.

225-45-18 = 25.97" overall diameter

 

There are a few pictures of FC's with RX-8 wheels on them, easy enough to find with a Google search.

The main issue is the massively positive offset of the wheel in my opinon, that could cause issues with fitment.