Bill Hirsch Automotive - 800-828-2061. They advertise 15, 16 and 17 inch trim rings. Ad in V8 Times. 17 inch only in chrome - $60 each. No 18 inch listed.
Bill Hirsch Auto in New Jersey advertises 15", 16" & 17" Wheel Trim Rings. He also has Stainless Steel Spyder Hubcaps, plus lots of other items to suit the early Ford V8 enthusiast.