I checked all the truck stops in my area for the same thing plus some other parts for my wheel simulators. I found mine were made by Dicor @
www.dicor.com.
However I had better help and was able to get my parts at
WWW.summitracing.com. For mine they are 10 stud, 2 hand holed, 22.5 inch wheels. Summit part number PHO-PN6256LNC for the lug nut covers. I think these parts are made by Phoenix. I was able to get left and right jam nuts and extenders there also. The covers were a little over $2 each. Theirs and the phoenix usa websites are very helpful. Good luck Darell