I used to buy wheel blanks from Stockton back in the early 1970's when I was running a 1/4 mile dirt track car about 40 miles south of them in Merced CA. We made our own centers from 1/4" steel plate and welded in right angle braces between the lug bolt holes. They were heavy, but they would take a LOT of abuse from wheel-rubbing with the other cars in the turns. We also welded in a piece of 1/4" steel bar stock around the bead area.

I doubt if any wheel vendor would sell a blank wheel without a center these days- - - -too much liability!
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!