Are you going to run these 18" 12 spokes on a FED ? Most FED racers run wire spoke wheels because they look nostagia and they are much lighter. Alot of the wire spoke wheels I make weigh 8-9 lbs each WITH tires, and can be as light as 7 1/2 lbs. One pound of rotating weight is equal to 10 lbs of static weight, and the old theory is if you take 100 lbs off your dragster, you'll pick-up a tenth. How much do your wheels weigh ? If your FED was orignally built with 17" wheels with tires that were about 22" tall, you may want to get 18" tires about 22-23" dia, or it will raise the front up higher than what you want, or you will have to change your front axle, or axle mount.
I sell some 2.00x18 German made rib type tires that are 22.75" tall, and 2.25x18 German tires that are 23" dia, also I have 2.50x18 rib tires that are 23.5" tall.
Goodyear and M/T both make 18" motorcycle front slicks, 23.5" to 25.9" tall.
So, what is the 18" application you are looking for ?
Feel free to call, 805-444-4489, Hayden Wheels
Jon