Regular 10 lug 18 wheeler wheels and tires can be used- - - -just rotate the lug pattern halfway between the existing holes and drill the wheels for the smaller diameter pattern. A machine shop with a dividing head on a Bridgeport mill would be the most accurate method, but a center for an original widowmaker wheel would make a very acceptable drilling template as long as it's centered properly. Either chamfer the holes for lug-centered wheels, or make a spacer ring to press onto the hub for a hub-centered wheel with flat lug nuts.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!